The ECU cannot be removed from inside the cab, it can be accessed/removed from inside the engine bay though.
Open the hood and look below and to the right of the master cylinder/brake booster and you will see the main harness. Loosen the main harness bolt (it's metric) and remove the harness from the ECU. There are also two nuts, and a rubber retainer, that hold the ECU in place (they're metric as well), remove the nuts and retainer. You will also have to remove some of the screws for the inner fender well so the ECU can slide out. Once you remove the nuts and screws, push down and away on the fender well and remove the ECU; it'll take a little work, but it's not hard and it doesn't take long at all.