The engine expects the base .kf files to be loose in the Meshes folder. No text files are needed by the game engine. Technically, the game doesn't care if the extra bones are in the .nif files at all. What it is looking for are the .kf files. The .kf files should open in Nifskope the same as any .nif. What you are looking for are toe and tail references.
xbase_anim.kf -> is the base animation for all male humanoid (non-beast) races
xbase_anim.kf -> is the base animation for all female humanoid (non-beast) races.
In nifskope, if you see entries called NiStringExtraData for bip 01toe or bip 01tail or any other bip toe or tail, right click on it and select "Block" then "Remove"
By default, non-beast, bi-pedal races don't have toe and tail bones. Only those races with beast-like feet and tails need them.
As always, back up your originals.
EDIT: there is no need to merge the files back.
Yeah, I would prefer to install them by hand rather than messing with the files. At least, I am going to try the manual install first. You say that there is no need to merge them back. That would mean, however, that the WalkForward;.kf animation, which is different for male and female would only be able to be in the Meshes folder once as you cannot have to files with the same name in one folder.
So basically what you are saying is that I just have to download the animations and then simply copy the kf files into the Meshes folder? Then again, how can I enable both the male and female version? How does the AnimKit install the animations?
And again, I cannot find any (x)base_anim(_female).kf files. Only base_anim.nif files on the CD.
Edit: Sorry, if my replies seem rather rude; your help is greatly appreciated =)
Edit 2: Are the steps above meant for installation with the AnimKit and not the manual way?