Clutch change/flywheel skim is a standard workshop procedure, any good mechanic can do it. For reference with workshops, you can find a list of them here:

http://www.perth-wrx.com/vb/mechanic...workshops.html

The list is a bit outdated (Maximum Motorsport have moved to Kewdale, STechnic are in a new location, some phone numbers may have changed so worth Googling them first) but it's a good reference list at least for workshop names and what they do. As far as Subaru specialists are concerned any of them on there are worth checking out and you can pick depending on your location.