Upholstering flat panels is pretty easy if you take your time and are smart about it like the thread originator was. You tape off to prevent overspray, and make sure to get the edge really good. You don't want to use too much glue that it puddles, or soaks through the new fabric. Also pay attention to the glue's strength. The stronger the better.

A technique I frequently use is putting a trash bag over the panel and slowly pulling it back while laying the material. That way you can have the material laying flat on the panel without it touching. It helps when you're trying to flatten in curves.