Here are some general directions to help you install a manual boost controller on a subaru vehicle.

1.  First you will need to of course get a manual boost controller, I am using an OBX mbc for this install, which can be found here on ebay for a pretty decent price.

2.  Disconnect the lines from the turbo and wastegate.  The lines that need to be disconnected are: the boost line that connects to the end of the turbo (the turbo nipple), and the one that connects to the wastegate actuator (this is just the round gold colored thing near the turbo)

3. Connect the manual boost controller lines in the locations that you just disconnected the old lines.

4.  Its as simple as that, your new boost controller is ready for you to go out and adjust.