JulzMighty, that's a pretty brilliant approach. Ironically, I can't seem to get both RTT and your shader working even though I've had no problems getting your shader to work properly in my environment and I've had no problem using RTT assigning the camera.bmap to a bitmap for a panel. Do you have any CScript code showing how you used RTT with your shader? Here's the code I've been using unsuccessfully:

bmap shader_postprocessor_camera_bmap = <postprocessor.tga>;
function mtlPostprocessorEvent()
{
mtl.skin1 = shader_postprocessor_camera_bmap;
}
material mtlPostprocessor
{
event = mtlPostprocessorEvent;
flags = tangent, enable_render, enable_tree;
effect = "Postprocessor.fx";
}
function ... (called once after game load)
{
...
camera.bmap = shader_postprocessor_camera_bmap;
...
you = ent_create(shader_postprocessor_bmap, temp, NULL);
you.material = mtlPostprocessor;
}