Why do that.. You can DL them on your computer then send them over to your BB through the device manager software or you can email them to yourself. There are sites (crackberry to name one)where if you are a member you can get some nice free BB song downloads.
Or sites like phonezoo, funformobile or myxer...... login and then upload your own edited (cut to less than thirty seconds) audio file and it will create a ringtone out of it. then you can send it to your mobile phone. They even have quite a selection of user-created files. right now im sporting the amazing "butscratcha" from familyguy! 😃