Editing or modifying disparity maps

i have a stereo situation where i want to fade the stereo depth only in a certain area of the image. my thinking is the create a disparity map, convert it to Z or color. modify the that with a matte and/or color correction to limit the effect and convert it back to a disparity map to plugin to to the stereo align tool.

of course, i haven't had much succes. am i on the right track? any help is appreciated.

Fade? Explain what you are looking to accomplish at the end.