I’m still just playing with Softimage and not 100% up on all the terminology, so there's a good change I have know idea what I am talking about here
and this is probably not what you want at all, plus I think it only works if your U.Vs are created within Softimage, (best to wait for bill! he's the man
) but you could combine them so that they are one object this will give you all your UV's in a single map. Property editor/ Model/ Create/ PolyMesh/ Merge the newly created object stores the different materials in clusters representing your former objects so you should be able to use a single texture map.
Edit: Don't take my word as gospel....try it on a test mesh first