I've done it!!
Here's how you play music that you've created beats to:
1) Create the Beat in TTR
2) SCP into your iPhone and navigate to: /private/var/root/Media/TTR/Taps/iTunes/
2A) Notice that there are at least one directories, that'll be the artist, go into it.
2B) Go into the song folder as well
3) Copy over the file it will be in this format: your_username.xxxxxxxx.tap (where the 'x's are a bunch of numbers
4) Rename the file to Artist - Song.tap (replace those with specifics).
5) Copy the .tap file back over to /private/var/root/Media/TTR/Taps
Now the tricky part:
6) Copy the MP3, or whatever the audio file is to /private/var/root/Media/TTR/Music/
That's it, go into TTR, and you'll see the beat that you have just created.
This, for now is what I've got. I just figured this out maybe 5 minutes ago.
In the next revision of this, it will hopefully be a hack that will link to the music folders and hopefully TTR will see it... I'm not sure yet on this. Maybe some help from someone who knows more about this app would be cool
