[caldrail]

It's possible up to a point. The actual files are sometimes in different places on peoples installations so I can't be too specific - use the browser on your paint program to find them.

Now here's the problem. The actual sizes and exact positions are down to the individual models with some hardcoded generic rules for which roundel or sign should appear. You might be able to script a mod to change the limitations of this (and it is a real limitation - different parts of the airframe model share the same graphic) but that's over my head if possible at all.