Hi Roger
Hmm, I see the problem.
There may be a solution. When I upgraded to CS4 I got a free 30 day trial to some Photoshop on line video tutorials at Lynda.com and I recollect watching one where the demonstrator used the “blend if” function.
The “Blend if” dialog is in the Layers Panel, under fx, Blending Options and you can set dark and light limits on say, the top layer which will only allow certain tones from the bottom layer to poke through.
This was several months ago and I haven’t used the technique, but it might be worth exploring.
Here’s just one random result from a “Blend if” Google search:
http://www.photoshopessentials.com/p...ects/blend-if/
Cheers
Dennis