Don't think any such thing already exists.
If you mean ones in actual VGM format, look up a program called BRTSM Convertor. It can convert to a format it calls "Looping Ogg", which has a LOGG extension. This is actually just OGG with some extra metadata tags that tell it how to loop - and NeoLemmix understands these tags.
(You will have to change the extension back to OGG, though.)
