I saw some posts here recently about such hacks, dunno where, but I think KBD translation was included.

You might want to contact Silicon Valley Bus Company, they had a product called KeyStone that did PS2 -> ADB for KBD & Mouse and a lot of other cool products.

Didn't find their site, they may not be around anymore, but the search turned up some interesting .pdf files, articles and such:

http://www.google.com/cse?cx=partner-pub-2070091971271392%3Aougxymc6y19&ie=UTF-8&q=%22silicon+valley+bus+company%22&sa=Search