The board uses a PIC microcontroller which takes the analog input from the touch screen and sends the data over I2C, using the same slave address as the camera. There's no software on the Wii side because the board is hardwired to a Wii Remote. It's not very adaptable right now (the code is written for the specific touch panel I used), but I'm working on a solution that would work for any touch panel.
BitBuilt - Giving Life to Old Consoles
JacksonS