I'm currently writing an import script/addon.
The file format is one vertex per line:
x, y, z, u, v
With 3 lines for each triangle (no quads).
So far I've got vertex's, edges and faces all importing correctly.
Now I just need to import the UV coordinates for each vertex.
However I'm having trouble trying to find a way to do this.
The best result so far was copying code from the UV operator template, which gave me a UV Map, but it puts the whole model at one point.