Disklavier

Hello.

I've inherited an older Disklavier:

  "It's a 5'10" grand "G2" with a MU50 synthesizer Diskclavier with the DK@10 Wagon"

What are my options for upgrading it?  I'm mainly interested in controlling it with a 
computer (via MIDI or some other documented protocol).

Thanks in advance for any advice,

Kevin