A hexeditor, patience and alot of time. None of these 3 I have right now
I don't remember well where I left of, it's been over 9-10 months since I looked at this. I remember I had found out how the bone structure was stored, but missed info on matrices and the weights of each joint (or perhaps the latter I did find out, don't remember). The big thing is putting it all together how the timeline is built with all the animations/poses, the transformations of each bone, etc. I have all kinds of parts but not the big picture due to missing info/understanding of some key areas of these chunks, stuff like relationships etc. I have spent hours upon hours finding links/relationships between the chunks (id's and stuff) but constantly ran into a wall... I would find out eventually but have no further interest.
If you find out, then perfect, but I really don't see me spend a whole big deal of time on it, especially since SH5 has a new animation engine (based on freely available tools I'm told by Dan).