I have spent about 2 weeks trying to figure this out. Everywhere I look, it seems that its either a dead end, or I get told that it just can't be done (Despite me seeing lots of videos that proves that its been done). Anyway, enough about what I've been going through to try and find this information. I've been following the info on this page (Bottom of the first post). I've, so far, extracted the data from the CPK, extracted the data from the Classic Sonics .ar.00 and .ar.01 files, imported the models into 3DS max 2013 (which was difficult to find), and converted the hkx animations into .kf format. Now this is the point I'm stuck at. When i try to import the animations into 3DS max, it seems that the bones get removed from the dope sheet (aka animation editor) or at least from view. I have tried importing them many times but to no avail. I know hkx animations are valid as i viewed them in the havok previewer. The imported model also appears fine in 3DS max. Any help is appreciated. I'm also on the IRC if that would be better for figuring this out.