Hey!
Bad news for you, state machine files are not loaded into any instance manager on the scripting side. You can access them, but only as a raw file and that wouldn't get you anywhere.
It looks like that exact CAS ASM file is used for walk styles in-game. CAS screen is in no way accessible from the scripting side, it's purely a client-side thing.
But, maybe this is your answer. Have you tried adding a walk style? Maybe that universally makes CAS use some idle animation at the same time. I can't help you with that though.
