do you really need a schematic for 14-16 momentary push buttons and 56-64 LEDS connected as matrix? I´m sure all you need, you will find here –> http://ucapps.de/
Well, I think the more difficult it´ll be to programm it
mbsid schematics can be found on ucapps.de, but this won’t help you much as the physical matrix buttons just control the routing inside the mbsid software, so the matrix isn’t something you can rip out and build separately to use as an audio or cv matrix.
the thread you’re searching for is here: http://www.midibox.org/forum/index.php/topic,11262.0.html. but this matrix project isn’t finished yet and at least in public didn’t show much progress in the last months. maybe you should post to this other thread to find out what’s the current status.