There is a japan domestic market part that will replace the auto climate controls (H6217AG902SC), and has an opening for a 2 din aftermarket radio.
Youn can see a picture here:
http://accessory.subaru.co.jp/legacy/catalog/book/audio/index.html#top
...and here:
http://legacygt.com/forums/showthread.php?t=12513&page=3&pp=10
I have a 2.0R and I'll install one of those as soon as my dealer gets one for me.