On a technical level, this could happen by:

Get a copy of WolfMame 0.139, a copy of the MAME 0.139 source, and a copy of the current MAME 2010 source. Generate a source code diff between WolfMame 0.139 and MAME 0.139. Selectively apply the diff to MAME 2010 You have a libretro WolfMame core

The first two steps might take a couple of hours to figure out and set up in a filesystem tracked with git.

The last step could take hours, days, or weeks. If it took less than 10 days of work I think a coder would be proud. It's totally doable, and if someone took the lead they would probably get some help.

Maybe this would be good for a libretro bounty.