I'd expect Dan or Sam to show the exercises you need to develop IP/IS. So why put time in learning some other form?
Secondly, who says that the specific IP/IS mechanics as taught by Dan or Sam are a perfect match with the mechanics of Chansi Jin or Chansi Gong?
My thought is the OP was from a guy who did a seminar with Howard, so he's just getting started. i.e. go play UNTIL he starts getting regular seminar lessons and solo practice going.
Second part of the thought was at the last seminar here in Seattle, Dan mentioned Chansi Jin, silk realing exercises. Dan has his curriculum he teaches, which would eventually be a model to follow, but again if you're a newb and just want to start playing right away...
I don't know the OP, but what if he has no concept of where his hip joints/kwa actually are and how to start using them? Many people don't - simple flowy tai chi can at least point you toward properly aligning your pelvis and understanding how to open/close kwa. That in fact is what started sending me further down the rabbit hole of this stuff and finding Sam, Dan, Aunkai etc.
again just for the complete newb to get started...