I search the web for this subject but can't find anything. Than I try this procedure.
If you want change Materials with corresponding UV's for object (especially for Character) follow this guide:
1) base UV tag are with Main object mesh, 2nd UV tag is importing or creating by you are on copy of Main mesh
2) add Pose Morph with checked UV to Main Mesh
3) drag 2nd UV in Pose Moprhs Pose target field
4) create Xpresso for swap Materials (search for corresponding Tuts)
5) add Pose Morph slider to Xpresso
6) delete link from Pose Morph target field
Now you can change all Materials and corresponding UV by one click in User Data