This template was hand-traced from some old Fleer stickers I still have from when I was a kid, probably around 1980 or so.

For best results, rotate your logo -16 degrees, and just resize to fit.  Hide layers you don't need (button, brim, front panel) and use the paint bucket (in GIMP) or the color overlay layer style (Photoshop) to paint the rest of the cap.  Easy-peasy!

For use with Out Of The Park Baseball, resize the finished product to 150x150 pixels.  Other games may have different requirements, which is why I left the template as big as I did.

Enjoy!