Ouch that sucks, i replaced mine when i did my cams but i had my engine out. I had the valve covers off and took out the rocker assembly out before you can get the camshaft plugs out. You can do it in the car but with that limited work room and having to take out the battery, washer tank, radiator and timing belt, it's was just easier to take the whole engine out. just make sure you get the Subaru liquid gasket along with the new plug to make sure it doesn't leak again. I'll pm you my instructions for the cams, it will give you an idea at least. I'll check around and see if there is an easier way because it seems like a lot of work of a plug that can leak.