Is anyone able to get RTR skeletons into BI?

[Cheexsta]

Trying to mod the game to use the RTR skeletons on top of the BI ones is harder than I thought. So far I've:
- Unpacked skeleton.idx/.dat for both RTR 6.2 and for BI.
- Added the RTR skeletons to the BI ones, making sure to update list.txt.
- Repacked the skeletons.
- Unpacked both RTR's and BI's pack.idx/.dat to add in the missing animations.

Now, at this point the game couldn't find a few of the animations that these new skeletons referred to. With Vercingetorix's help (thanks once more), this has been solved (the first error was "Filename not found: Stand 2 push heavy object.cas" - this (and all later errors) was fixed by repacking pack.idx with another line added to anim_list.txt). However, now I seem to be getting this error:



Anyone more competent than I able to do it?