you can get an encoder from ebay quite cheaply , the keyboard can be of your choice
there are a couple helpfull links in the below link
this was the unfinished project but funtional , something that could possibly let the imagination run wild
http://www.cnczone.com/forums/showth...=keyboard+hack
a link to switches , ive got two dozen coming , they are dirt cheap
http://cgi.ebay.ca/ws/eBayISAPI.dll?...B:EOIBSA:CA:11