Yamaha DTXpress/DTXplorer/DTXtreme

ok,  I used the DTXPRESS for a live Jam practice with some guys last 
night.   It worked great after some fine tuning.    I have a question, 
maybe you guys know is there anything on the market that will allow us to 
play cover tunes and fill in the missing parts?  Like if we want to play 
Dave Matthews  tune "what would you say"  is there some piece of equipment 
that will allow me to hit Play, hear a click so I can start the tune, and 
then fill in the Harmonica part, and violin part.  Or If I want to play 
that rusted root tune,  I can go get something or download something that 
will cover the flute part?  Does anyone know what I mean?

Herb