Wow! AOS replacement on a 12 yr old Boxster S is an exercise in patience. As a DIY, be prepared to spend at least 3hrs in the garage.
It took me nearly 10 minutes and a lot of persuasion to get the clam shell in service position, before even removing any of the throttle body assembly or intake T's. Because it was fairly cool, I raised the top to service position in multiple stages, making sure there were no creases in my possibly original plastic rear window.
I have a maxjax lift, so I was able to raise the car to 24" and 48" heights to get at the lower spring clamp on the bellows piece. I worked on it on and off with multiple breaks for 3hrs, and I just now have the new AOS in place (a little bit of the red "o-ring" is showing out of the block. Don't know if this is normal. About 1mm or less of the oring is showing. I don't seem to have broken any of the clips for the connectors or hoses, so that's a plus. With the maxjax, I was able to get the car into a comfortable position for either working underneath it, or through the wheel well while sitting on a rolling stool.
The middle plastic tube connected to the AOS was a pain to get to. Hardly any room to work in there, and my fingers weren't strong enough to pressure the clips enough to get the hose disconnected. I finally was able to free the AOS into a position where I had better access to that clip.
Tomorrow, I've got the intake crossovers to clean up, and various wires to reconnect. I removed a wire clip from near the bellows to get a better access with my remote spring clamp pliers from below the car.
Luckily, the weather was very cool (ambient temp was around 5C or 40F tonight, so with long johns on and a sweatshirt, I was relatively comfortable in my garage. It's a medium difficult job, just cause u're working blind for most of it. At least I didn't have sweat dripping off my forehead.
Peter