Eml synthesizers

I would like to put a midi kit in my 500.  I have one of John Hill's 
Synhouse Synjack interface.  It is small and adapts to the control 
voltage of the EML systems.  It doesn't have pitch bend, and is 
pretty much a note on, note off system.

I really like the Kenton kits that I have in my Odyssey and Pro One, 
but they never made a kit for the 500 and they are out of the 
retrofit business now.

Has anyone found a good installable solution for the 500?

Also, anyone have a 500 manual that I could get a copy of?  I have 
some interesting items to trade.

Thanks