If anybody is interested, I found my old AB3D 2 mod. Not sure it is complete, but here it is regardless:
http://extropia.co.uk/projects/KarlosTKG.lzxExtract it somewhere (it creates KarlosTKG as a directory), put a copy of your tkg executable from your original game in there and run it from the KarlosTKG icon, which should set up all the assigns.
What you get are slightly modified / reskinned levels (a few new secret areas here and there), reworked weapon models (alas some of the animations are too fast in UAE), new monsters, effects etc.
I was rather pleased with the models (reworked the shotgun, assualt rifle has ejecting brass, muzzle flash, grenade launcher has rotating circular clip, also added a chain gun), making them with the provided editors was a complete bitch.
Due to extra models, sprites and textures, I think it may need more RAM than the original. It has never been tested with less than 68040 / 16MB. For some reason, the mod really does not like the RTG patch and will crash fairly quickly.
Have fun, all bug reports to /dev/null