CreateObject pos=314.25;250 dir=1 type=EventEntity script1="%lvl%/DoStuff1.TXT" run=1 selectable=0
This could handle different mission events. Regular objects in game can't run programs. (If that was the case I'd run a global program on any cactus)
Lazy solution - enable greenery or other static items to run programs on them, via scene.txt file.

Regular solution:
This could be possibly achieved easily by duplicating AlienAnt definition, changing name and deleting 90% of references to model, animations, collision sphere etc which should not take that much time but gives a neat tool for level design.

I had to use stationary aliens for this in my missions, and pretend that they're standing still for artistic reasons.