So this is an old issue, and mostly well documented here: http://legacygt.com/forums/showthrea...ix-197481.html
I didn't see any pics though, so I went ahead and took some when I recently changed mine out. Part number needed is 34439FG000, they were $1.85 at my stealership after I told them that $4.xx sounded ridiculous.
First pic shows the area you will be working in. In between the alternator and inlet. If you have an alternator shroud like I do you will want to remove it. Second pic is a bit closer in.
Third pic. Remove this bolt.
Fourth pic. Over to the right of the alternator and on the bottom side of the bracket. Loosen this bolt just so you can move the bracket out of the way a bit for better access. I don't recommend removing entirely, as there is another bracket on the backside of this bolt and you don't want to drop that. Plus there's no need.
Fifth pic. Now go back over to the power steering side, swing the bracket away a bit, and remove the 10mm bolt securing the line. Don't worry, nothing will leak at this point since you are just removing the bolt. In the pic, you might see that I unclipped the sensor there but you don't need to do that.
Sixth pic. Your new gasket!
Seventh pic. When you remove the line/fitting, you want to quickly lift it above the level of the fluid reservoir that is all the way over on your left on the fender. This will prevent you from losing much fluid, but have some paper towels / rags ready anyway. Avoid leaking fluid on any of your belts. In this pic, you can see that I propped up the line with a screwdriver against the alternator, worked pretty well.
Eighth pic. Coat your new o-ring in power steering fluid (ATF Dexron III in our case) and seat it COMPLETELY down in the pump. You could also choose to seat it on the line itself, but this is how I did it. If you coat it well and seat it well, either should work.
Then reassemble. The only tricky part is getting the line back in there quickly as it will want to leak once you start to bring it down below the reservoir level. Just put it in place, and gently wiggle until it starts to seat itself and then press it all the way in. Good to go.
Top off the reservoir as needed and be aware next time you drive as the system will bleed itself a bit as you drive and use the steering.