tho thinking about it. there's nothing to stop you re-writing an OBJ's UVmap on the fly using Python..

you'd have to have temp files tho... one for the original UVmapping and for the Donor UVmapping and it would mean altering the OBJ file before loading... you'd simply block replace the UVMap in the OBJ txt enmasse...

clumsy... but it would work but I'm sure there's a better method.... thinks