I asked this question in a Blender forum but I've realized that MakeHuman does what I'm trying to do myself in Blender.
In Blender I can uv the clothing and apply textures to a standard A-posed human and create a .png texture file. What I can't get my head around is, when I subsequently change the pose of the model, the .png file no longer "fits" the new pose. Blender/MakeHuman seems to be able to handle clothing repositioning when creating new MakeHuman poses since no uv'ing is required (you simply download a clothed character to Blender from MakeHuman, set up the new pose and send it back to MakeHuman. The clothes still fit!). I'm trying to export my character to a program that requires a .png that matches the pose and, because of other requirements, I have to do everything in Blender. I'm not skilled enough to manually texture a contorted figure so I'm hoping someone can explain how Blender/MakeHuman accomplishes it.