Well, I've tried getting Marines to drive warthogs through command lists, and it seems to work fine in Sapien. I also made the driver blind and deaf, just so there aren't any distractions. However, they never really finish it. My script involves:

		(ai_command_list driver escape)
		(sleep_until (= (ai_command_list_status (ai_actors driver/driver)) 1) 15)
		(ai_command_list driver escape2)

which waits for the first command list to finish. It works in theory, it works in Sapien, when i run_game_scripts. However, it won't work ingame. The driver stops halfway through the second command list, and refuses to keep going.

Video:
http://www.youtube.com/watch?v=XeDoWOj75VY