I have a 1993 Mitsubishi 3000gt and the TCU is located under the console / dash. It is mounted by a metal bracket to the floor pan. You will need to remove the side carpet panels and the entire front console to access the TCU.
Disconnect the battery. Unplug the alternator and take the belts off. Unbolt the alternator, and bolt the new one in. Put the belts back on it. Plug it back in and reconnect the battery. Voila! You changed your own alternator!