I reported this annoying bug to Adobe.
Hopefully it will be fixed in CS6 or whatever it’s called
I am on vacation and don’t have CS5.5 on me to try different ways, maybe create the KF, select the keyframe and delete it and make type value again…
The internal inpoint in CS5.5 is always at frame 0 even if you change Premiere in-point. To offset the start point frame (what becomes the first frame in Twixtor), you offset it in a subclip.
Pierre