Quote - Short of taking the whole mess into the cloth room and doing a full conversion (defeats the reason for using conforming clothing)?

In my humble opinion, defeating the reason for using conforming clothing is a good thing. The only thing conforming has going for it is that it's convenient - and once you've started tweaking and adding to it, it's no longer convenient and you may as well do the job properly. That is, by tweaking and adding to dynamic clothing. :)

That said, the morph brush is just that - a creator of morphs. If your clothing mesh doesn't have enough polys in the place where you want to add wrinkles, and if the original creator didn't put them in, it won't have, then you may not have enough mesh to add convincing wrinkles.

My vote would be for displacement maps, since these work on the micropolygon level and are independent of the mesh. These are not so easy to do, admittedly, unless you have a 3D painting app.