Resurrecting this thread with 2006 replacement procedure I used. My wife's G6 was leaking oil, and apparently from this gasket. My first fix was to just tighten the bolts. As stated above, the bottom bolt is buried behind the A/C compressor. I bought the replacement gasket and waited for the next oil change. Here were the steps I used...in my garage with no special tools; took me two hours, but I was working with one arm in a splint; you will be far faster if you have two 'good' hands!
1. Jack the car and put front up on stands
2. Warm the car (just enough) and drain the oil.
3. Remove the filter and let drain completely.
4. LET THE CAR COOL DOWN! The exhaust is RIGHT there and this fix is a burn waiting to happen if it is hot.
5. While the car is cooling, remove the air intake hose across the front (two band clamps and one 10mm bolt in front of battery)
6. De-tension the serpentine belt (1/4" drive socket wrench or breaker bar), removing from the upper idler. Let the belt stay there and note how it is run--good time to replace if it is old.
7. Loosen the upper two bolts (15mm) that hold the A/C compressor to the block; remove the right bolt, but leave the other one threaded in several turns. This will support the compressor and the spacer that sits between the compressor and block while you remove the oil filter adapter.
8. Assuming the exhaust pipe is cool, remove the 15mm A/C compressor bolt on the bottom. The compressor will now rotate enough to clear the bottom filter adapter bolt.
9. Remove the three filter adapter bolts (10mm) and remove the adapter and gasket. Note the position of the filter; the 'U' shaped hole is behind the bolt that is blocked by the A/C compressor.
10. Clean off the face of the adapter and the engine block.
11. Replace with new gasket (available at all major auto parts stores; actually was in stock at the "O" store in town).
12. Position new gasket on housing with upper bolt to 'hold' as you reinstall. Get all three bolts started and finger-snug, then position the adapter 'in the middle' before tightening first bolt--it can slide a bit each way. Seems there should be a guide pin to hold set, but there is not one. I centered it between the free play and snugged up the bolts.
13. Torque the 10mm bolts to spec (14lbs I think; confirm that, though)
14. Reinstall the lower A/C Compressor bolt but leave loose.
15. Reposition the spacer and reinstall the upper bolt you removed (a pain when you only can work with one hand). Torque all of the A/C bolts to spec (do not forget about the lower one you left loose).
16. Reinstall the serpentine belt and air breather hose.
17. Reinstall oil drain plug and new filter.
18. Check the belt is centered in the pulleys and all bolts are back (none left over).
19. Fill with oil, start, and check for leaks (and no squeals from the serpentine belt, especially with A/C engaged).
20. Shut down, take off of jack stands and you're done.
I noticed that the OEM was a soft metal gasket with a thin silicone or other cushion on each side. The replacement gasket I got (Felpro) was more traditional with a 'soft' coating the entire face of each side of the gasket. Can't complain too much...OEM lasted 100K miles before the leak started.