I've successfully done the 4EAT diff lock mod on a few JDM Foresters. 98/99/00 ST/B and STI. This also works on JDM auto Legacy/Impreza's.
It's probably the best mod you can do on an auto Subaru. Effectively doing away with the crazy torque steer we get on the higher HP JDM's.
About $30 in parts and just over an hour to install.
Props to previous user's who have done this years ago. It's been around for a while already
http://www.rs25.com/forums/f8/t99075-4eat-diff-lock-switch-handbrake-mod-torquemada-lite.htmlThe only difference between US and JDM Subaru's is the pin out on the ECU. For JDM's it's the white/green wire that you splice into. Pin 15 in connector B54.
I did cut into the center console using a small dremel tool and put my switches there. They have been since labeled. The left is lightbar and right 50/50 auto lock.