HoMM VII Haven Units – Haven faction units from the seventh installment of Heroes of Might and Magic.

Not bad.
How did you eventually "adapt" it? Did you remake the skinning from scratch or manage to transfer the existing skinning information to the new skeleton?

It involved a lot of trial and error with the original skeleton of the Fortress creature from Might and Magic VI. The main problem was mirroring the model, skeleton, and skinning while preserving the "default" coordinate system because if this system isn't identical, it will be a mess.