You can add comment field tag to your shared mp3 files using e.g. Tag&Rename. That is the only legit way. Just something like

"Go to C-Murda on MySpace Music - Free Streaming MP3s, Pictures & Music Downloads for more music from me"

note: only in your own tracks or it's spamming. People hate spammers.

If you meant creating redirects to your myspace in Limewire search results, then that is considered spamming and very bad etiquette. And it would result in people hating everything you do or stand for.