How do you make a model use the UV map of another model?

What is it you're trying to do exactly? Or is this to do with what I posted on SWBFGamers?

I can tell you that what I did was deleted one side of the mesh, then projected it onto the original texture (though it's not actually that simple as you have to then manually move points and place the verticles appropriately). This was done in Metasequoia because it's easier for me to do it - the only drawback is having to export as OBJ and import it into Mod Tool and re-envelope and weight it.

In XSI you can use GATOR to transport UVs. It doesnt always look pretty though. You can google GATOR or look in the help section of the program.

It's partly because of what ggctuk released, but also because I wan't to modify the BF3/TFU Clone model to use the BF2 clone texture.

That would take a lot of work to do. A lot. It took me roughly 3 hours to get the UVs on just the Wii TFU 501st Stormie helmet mapped right to the stock Stormtrooper texture, and there were less triangles that I had to work with.