While in my advanced texture and lighting class during this summer, I came across an amazing UV unwrapping program called UV Layout by Headus. Unlike Maya, which has limited tools for doing UVs, not to mention the time it takes, UV Layout is fast, and far easier. It can read OBJ files and saves the UV maps into a new file or the existing one. You can then use Maya to transfer the UVs:
- Select the imported object with new UV maps
- Shift select the destination object in the maya to copy to.
- Set the Menu to Polygons
- Select Mesh
- Select Copy Transfer Attributes
- Select UV Maps to transfer
The Headus website has very good video tutorials as well.