For an AI loco, make a copy of the *.eng file and rename it to *_ai.eng (or whatever helps you know it's an ai). Then open up the *_ai.eng file in wordpad and find all of the Engine, Wagon, and Name entries. Add the _ai tag to each one (or use whatever config you used when renaming the *.eng file). Then find and delete the Cabview line as well as the Headout line (some locos won't have this). You can also delete the sound line that includes the cab.sms file. Save your new _ai.eng file and create a consist.

(Somebody correct if I left anything out--it's been a little while since I've done this.)