Personally, I optimize the meshes by hand using Editable Poly. Like Eric said, if you use the Remove button for verts and edges it will keep the UV's. Plus Max 7 has an option to move geometry without affecting the UV's, very handy. This way you end up with a clean, efficient mesh and can keep your edges right where you…
Apparently Max 7 has a way to project UVs from one mesh to another. I haven't tried it yet though. Barring that, best bet IMO is to use Editable Poly and remove edge loops (or rings) manually. Should preserve the UVs. MultiRes tended to chew up the topology for me, making the lower LODs not nice to deform... edges tended…