With this little tool, when you deal with layout jobs you can simply put every objects as well as control points to the right place looking through your reference camera, then use this tool to give them right depth along the camera.
A short tutor
For the following example
The left view is looking through the persp, and right view the renderCamera.
After installing this tool just like other mels, type and run suCameraSpace in Maya, you should see a window comes out as the first image indicated.
Select your render camera, which the reference image projected from, then click the small arrow button next to the camera text field.
Set the offset value as you like. 1% Should be a good start to go.
Now instead of tweaking the objects and control points in both views over and over in order to match the reference image precisely, you can just put the object in the right way base on renderCamera view, then go to persp, use the bottom four buttons to located any objects and elements! The first and the fourth is 10x gained. It's very simple and effective.
Hope you like it! :D
Tested on Maya2010. If you find any bugs feel free to mail me: cuckons[at]gmail.com