You want to weld in a new O2 bung on the drivers side header just after the collector angled at either the 10 or 2 position. If I recall correctly there is an HOW TO on this site or on one of the other sites devoted to HD's & L's (lightningrodder, nloc, etc...)

Got no idea about tricking the ECU, but that is something I wouldn't do as I would think it would just cause more problems. Also the stock position for the front 02 sensor is farther back then where you want the A/F 02 sensor installed.