It's a bit complicated so I'll summarise as clearly as I can.
The basic principle is this, you can get the machine into a state where you can't get the face hugger (I'll refer to it as alien) off the bonus gamble until you get a win banked, so you just need to make sure that win is the jackpot. The feature 'Out Of This World' is a jackpot feature, so you use the 'no lose' bonus gamble to get steps + extra life + lucky seven to make getting to it possible. The machine doesn't block it as hard as it should.
(For the jackpot on Out Of This World you need to get a total of 18 in view on the hi/lo reel, I find the best one to aim for is the 8/10, as it's two steps after the 9/11+b which is a good sighter and you'll be used to hitting anyway.)
So here's the method.
1) Check that the game is boarding on 30p play, any win is what you're after, or even a hold after nudges for three different symbols counts. This shouldn't take more than about five or six quid. (It'll always be boarding in the emulator unless you've properly hammered it, out in the wild this was the test to see if the machine had been battered.)
2) Go up to £1 play and lose exactly £40. Don't collect ANYTHING or the bonus gamble trick won't work, avoid wins and features as this just slows you down, literally just lose £40 as fast as you can.
3) Go back to 30p play and play for a low win, preferably oranges/mixed sevens/single bars.
4) Now you are on the feature you are aiming to get to the 8 KOs square with three steps, extra life, and lucky seven.
You can't get aliened on the bonus gamble as long as NONE of the following are true - you have a hi/lo gamble available that can't be lost, you have £5 or more on the cash stack, you're above 8 KOs on the feature (imagine there's a 'line' straight across the feature board above the 8 KO level, so bonus gamble on Face Hugger, 8 KOs, 5 Star Strikes etc is OK, but 9 Reel Blasts, 5 Win Spins, Monster Cash etc is not).
The £5 cash stack and 8 KO line are simple enough, but the hi/lo gamble needs a bit more explanation.
Basically if you have a 1 or a 12 to gamble on, or you can step to a 1 or 12, or you have a no lose, or you can step to a 7 with a lucky seven, or you have a hint - you are considered to have an unloseable gamble and the bonus gamble will alien you if it wants to.
The problem with being aliened is it can give CASH OR BUST and any win at all (even a quid) will reset the bonus gamble and you need to put another £40 through to get it back to the no alien state.
Safe number combos you can always bonus gamble on are 10/4, 4/9 and 9/11+bonus - none of these step to a 1 or 12 even with three steps, but they do if you have a lucky seven so you always want lucky seven last.
5) With all that in mind use the bonus gamble as much as you can, always take extra life if you are offered super bonus as it's most reluctant to give extra life. Hopefully it will give you the three steps itself. Once you have the extra life and three steps, keep bonus gambling until you get reel skill, and land this on 9/11+b, you want lucky seven. (If you get a lucky seven anyway, then happy days.)
Be smart with using the bonus gamble, for example if you have no steps then you can bonus gamble on any numbers as long as you don't have a 1 or 12, once you've got a step then you can bonus gamble as long as 1 or 12 aren't a step away, and then same again with two steps. For example 5/7 has no 1 or 12 within two steps so you can bonus gamble on that if you have two steps, but not three steps as that can get you to a 1.
Do be aware that the machine will often make getting everything set up quite hard work. For example any time you get a no lose or a hint then you immediately have an unloseable gamble so you have to take a hi/lo at that point whatever numbers you have on the hi/lo reel.
You want the lucky seven last as 10/4, 4/9 and 9/11+b step to a 7. If you get given a lucky seven try to get rid of it if you still need bonus gambles to get the other stuff, it likes to alien you if you have a lucky seven as it's almost always possible to get an unloseable gamble set up.
It also loves to give reel skill when you don't want it, (i.e. you're already on 10/4 or 4/9), stop it on 10/4 or 4/9 again so you can keep bonus gambling - sometimes you will need to do this many times, especially when it's tightening up.
Generally speaking it'll let you gamble to 8 KOs on pretty much any numbers as long as you're not blatantly reversing (lower than a 4 for example), so don't be afraid to push on up the board when you have to. Remember you can't bonus gamble once you get above the 8KO line on the board, any higher and it can alien you.
6) Once you have all you need gamble to 8 KOs normally, it should let you do this as it doesn't see the threat yet. So you're at 8 KOs with extra life, three steps and lucky seven, hi/lo gamble to the left going with the number, this should win.
Now gamble right to Streak, this will most likely take the extra life (if it doesn't it can be done at least another two times). Now gamble again to Streak, this should win and 90% of the time you will be able to step to a 7 with your steps, which with the lucky seven is a no lose gamble to Out Of This World - jackpot! The only way it avoids this seems to be 10/3 which you'll get occasionally, but you can step > step to a bonus which often gives change number and changes to a 1 for the Out Of This World gamble.
7) Once you've got your jackpot off Out Of This World, return to Step 1! I often found the Aliens here had three jackpots in them, sometimes only two, occasionally four and on one occasion five. Profit per jackpot was usually £15-£25, and it'd take me about 10 minutes for each, so £60 up in half an hour was pretty much the benchmark - not bad going!
EXTRA NOTE - Not every board will let you get the setup you need, it's far better to just accept defeat on the board than risking an alien on the bonus gamble, so if you can't get to Out Of This World on the current board just let the game kill you off, it'll board again shortly. Getting CASH OR BUST off getting aliened will cost you another £40 if it gives an award.
EXTRA NOTE - Once in a blue moon it will alien you when it shouldn't. Very rare but does occur, you just have to suck up the fact it'll take another £40 to get the bonus back again.
EXTRA NOTE - The above method isn't the only way to do it, you can try different approaches with less than the 'full set' of extras, I've got to Out Of This World from the 9 Reel Blasts side for example, or with only a couple of steps and the lucky seven - just play around with it, even better as there's no real money at stake in the emulator
I've seen a video of a real one taking £73 for a board (!) after being properly caned, haven't quite managed to replicate that in the emulator, current record is £54
They do tighten up though if you get them on or slightly over percentage, and they'll mess you around for ages with bonuses you don't want, like hitting CHANGE NUMBER seven or eight times on the trot from the bonus gamble.