So it seems all of the technical hurdles are out of the way to replace "lost" mutants in Xavier mode. Here is a run down of how to replace Wolverine with Shadowcat. This should work on a Pro (1.05) or LE (1.24) as both the Wolverine image and his name for Xavier mode are in the same location on both. This also does not overwrite or reset scores, audits or game setting, but if you choose to go back to the stock software I believe everything will be reset to factory.
Download the latest version of Pinball Browser. Currently 1.85 (find the link on the top post of this thread):
http://pinside.com/pinball/forum/topic/acdc-display-and-modify-dot-matrix-images
Download the X-Men software here if you don't already have it:
http://www.sternpinball.com/GAME-code.shtml#
Download the Kitty.png image on this post.
Then start Pinball Browser and click "Open" and browse to the X-Men software.
Then click the "Macros" button and paste this in the window:
Message,0,0x5DF,R"SHADOWCAT"
Image,0xD0C,"C:\Kitty.png"
Then click the "Run" button. You will get a Confirm box...click "Yes". Then a window will open that is wanting you to browse to the kitty.png file you downloaded. Browse to it and double click.
Then click the "Save as" button and it will ask where you want to save your newly modded software. I would give it a name different than stock so you can easily see it is a modded software.
The software is ready to flash. Happy hunting.
Kitty.png