Use Paint if you have Windows 7 or 8, older Paints screw up the image when you save.
Otherwise use Gimp.
Download both the PAL version (black) and the US version (red) of the cover.
Use same cover's both versions, so US Pokemon Puzzle League with PAL Pokemon Puzzle League.
Open both in Paint or Gimp.
From the US version copy the box and bit extra, maybe hal inc.
Just don't copy any of the red part.
Now paste that piece over the area on the PAL cover matching the background.
Save and your done.