In case anyone is wondering how I did this, here is the breakdown:
Backdrop:
Plain cabinet:
Lighting mask. I used partially transparent gradient objects that can overlay each other and then converted them into a flattened grayscale image that could be used as a mask applied to an all black layer. This allowed me to easily overlay seperate lights in an additive fashion and move them around without tedious manual work. I blurred the final image to give the lighting a softer feel:
Resulting positive lighting (white is transparent...):
Finished cabinet with lighting:
In Xlobby, I have a gradient background on bottom, followed by the cabinet backdrop, followed by the DVD covers, followed by the finished cabinet, followed by the DVD screenshots, followed by a button to cover or show the doors.
I also replaced xresource-selector-square.png with a light cone looking one. Unfortuneately this png is also used by the other databases, so that could be a problem.