Chris,
If you haven't used the thing in awhile, it's likely that there really isn't much in there anyway. I went through this on both my cars, and when I used a screwdriver to press on the release valve (after carefully covering my head and averting my face), I was greeted with a whole lot of nuthin!
I've done this job on the SC and the Carrera, so if you need help, just let me know and I'll be glad to come up and give you a hand. You buy the beers of course!
ianc