Finally something I know!
Key files are easy to make (I use PuppetJedI, but I'm pretty sure my version's out of date by now), but the best way to make a pup file is to take one from the game and edit it via notepad.
For a PC, use the ky.pup (Kyle's pup gives you a wide range of possible movements), for an NPC enemy use the st.pup (the stormtrooper default has fewer movements), and for a vehicle, find the pup that corresponds to the Lambda shuttle or the Crow
(which generally only have two movements).
Once you figure it out, pup files are way easier to edit than cogs.
"The Beasts know much that we do not." -Ancient Jedi proverb