Rig up the model in Maya using either the CoD4 or CoD5 charmesh
Set your char xmodel to the type 'animated'.
Set your char xanim to these settings:
Anim File: Your XANIM_EXPORT that contains the anim
Model File: XMODEL_EXPORT that contains the unedited pose of the skeleton with joints (doesn't have to be your model, can be any model that contains the same joints as the rig, or an export of the rig itself. I just export CoD_DefMesh.mb)
Done.
Credit: Treminaor