[Jeff-Groves]

You can combine meshes into one obj file. They are still separate meshes If done right.

Then Bake. You only need the UV's (VT) for each mesh. Faces should not change.
Don't know if Wings3D or other programs can export UV's only or if you can have more then one texture channel in them.

Now. UV's are a quick way to change texture coords (VT) in Max. I burn AO in a different program, save the UV's, then import to Max.

To do the same if your program does not export just the texture information? Export the burned obj and copy paste the VT's when needed.
And before anyone asks? I can decode 3D Max UV's to vt's.

Read up on how the obj file handles faces. It's really simple once you fully understand it.
3 verts make a face. The f tells you what v gets what vt
f v1/t1 v2/t2 ....