What I remember
JB,
From what I remember when I did it was just unplug the main electrical connection, a couple of screws that hold the ECU in place, and it's out. Reverse the procedure to install new one. I can't remember exactly what it cost, but I think I got my replacement at cost for around $200 (4 years ago). Hopefully someone who has done it more recently can give a more accurate cost estimate.
Good luck and HTH,
Kit