Hacker by the name of Redline99 released this tool
"This is a small tool that will remap bad blocks in a full 16mb "zeropaired" (xbreboot) nand image. It looks at the original Microsoft backup (that you should have) and figures out from the spare area the remapped bad blocks. You can also enter the block id's into the textbox. It does not modify the original MS image, but it does modify the zeropaired image. Run the app only one time, be sure to make a backup beforhand."

Download: Here