attessa split comes off the ecu on a wire that tells the system how much to split, not sure what pin, someone else (brad) will know.
boost you need to take off the MAP sensor, which, you are lucky because the S2 has and S1 doesnt. Look in the EBC thread it will be in there what pin it is, i think 52 or so.
Volts, pretty simple one there.
Not sure how it will fit as far as being DIN sized goes through, due to those like, metal bits on the side.
I would have bought an S2 RS4S gauge DIN from yahoo.