They say a picture is worth a thousand words. So this blend file is probably worth 1000*current.fps.
You will need Blender to open the file,
Just hover your mouse over the 3d view, and left click on the plane to start painting.
The texture us UV mapped to all 9 planes, so you can immediately see what the borders will look like.
When you like what you see, hover your mouse over the 2d view, and press F3 to save your texture. (Alphamap, and bump map sculpting version comming soon.:D )
Well, that is the gift to the community, now for the request.
Can you Ashley, (maker of all things cool in C2), please make a feature that tiles the current image, to the edges of the canvas?
This feature would be extremely useful for creating seamless stuff for our games 8).
Have fun with the painter everyone! I will make a better version, and post it in the next few days.