On YOUR car, the ECU, is located on the front passenger side floor on the left. There is a plastic panel next to where your passengers left foot would sit, pull that off, it will expose a steel box (the ECU). Unplug the looms from it and there are 2 Phillips head screws holding it to the car, undo those, take the ECU off the wall.
One end of the ECU will have like a lid that slots on over one end and it held on by 2 nuts or something similar, undo those, slide the lid off and the memcal will be staring you dead in the face. Unclip it, send it off.
Just remember though, if you take it out and send it off, your car won't drive. I suggest going to the wreckers and buying a spare VN - VR V6 memcal and sending that off so you can drive your car whilst Foamy does your tune as it may take a while because he is a very busy boy with tunes and what not.