You do know about GlobalOscActions? It’s a lua file that sit in the Renoise application folder and contain all those default mappingshttp://code.google.com/p/xrnx/source/browse/trunk/GlobalOscActions.lua
So you can produce a fancy GUI using TouchOSC, and set up Renoise to respond to certain commands by hacking into this file.
Related topic: Osc Discussion (How Where What To Use Osc)