Okay so I found this page on MediaFire where a user named TheOGB uploaded extended version of the character themes from Marvel Vs. Capcom 3. I know I've been wanting to use them in MUGEN so I figured others would too. I don't know who ripped and extended them so I guess it was TheOGB who did. I suggest downloading them individually as the pack he uploaded does not have them all.
Link here:
http://www.mediafire.com/?oq724im5f8u1a