There's an easy way to do this and a hard way. I'll just go with the easy way.
From Tleilax AP go 3 north, 2 east, 2 north and east, then wriggle through the gap. You might run into a shadowy figure, if not here, then inside, which are quite tough. Keep following the alley, there are more shadowy figures, all aggro probably, and a drunk, possibly aggie too. At the end, you'll see Korba.
Korba sells an IDstick and a cloak. You could just go 4 east, enter from AP and buy a stick, but it's cheaper from Korba, plus you'll REALLY want the cloak. The hard way is not to buy the cloak, and possibly dying pretty quick to some pretty tough mobs. There is one thing you should get from Vrastec though, and that's the locator for 10,000 solaris. You'll also want climbing gear, sold on IX: e, 2 north, e, south from IX AP.
Be sure to wear the cloak, if it doesn't fit, take care of that first. Then, go out the Tleilax west gate and head to: 28,43. Now climb mountain and look around, you should be able to enter the cleft. Just follow and look around, with your cloak on, you should blend right in and the guards won't attack you. You especially don't want to get attack by the Head Guard and his friends.
Look around until you find the BG tank, not BGW. Should be south, maybe twice from the head guard, then west. The guard outside has the password, which is mothersuperior. Examine it closely, and the hatch, and you'll know what to do.
Along the way, you might have run past a room with monitors. If you did look monitor6 there, you will have noticed how the master pulled the glowglobe and disappeared. Head all south from the corridor, and do the same. South of here is the master, don't bother with him. Head instead all north, and you'll find the archives room. Look at drawer8 and take the disc.
That's it. Now get out, keeping the cloak still on, get out of the forest and head to Wallach.
On Wallach, go 4 east, push bark then follow the northeast passage to its end. Once there, push stone and keep going north. If you disabled the tank correctly, just hand the disc to the mother for quest completion.
Reward: 5 quest points, about 300,000 solaris and more than 10 million xp. Not sure about xp, as I hit the cap.