Dune MUD

Solution

This quest actually has nothing to do with physically breaking into the Tleilaxu Guild.

Go to Talon's area in the Tleilax Forest (a hut found in the northwest corner of the forest, after crossing the bridge) and 'pay alms' to get in.

Kill the Acolyte at the entrance and take their dagger (Assassin's Dagger) back to the main TLX area.

Head to the smuggler in the hidden alley (from TLX AP: 3n, 3e, 2n, wriggle, ~2s, climb crate) and type 'trade dagger'. He'll give you a security pass / card.

Head back to Talon's area, find the safe, and type 'scan card' to open it.

Done! Don't forget to thank Math for this info, you little cheater