I just installed my piston / cylinder last night. You do not need a ring compressor. There are tabs (or skirts?) on the actual cylinder (front + back) so when you are installing the cylinder over the piston, you can squeeze the rings on the left + right side and slip it over.
Make sure you secure the KIPS shaft when you are taking the LEFT HAND NUT off.
Make sure you have a new top end gasket kit. Mine came w/ everything...more than I thought! The 3 KIPS cover gaskets were in very bad shape when I took the covers off. The KIPS shaft that drives the paw gears has 2 seals, which I forgot to replace (

) but in retrospect the looked fine.
I would get some easy off, or some other oven cleaner. The carbon build up on the KIPS valves is very tough. Degreaser alone would not get it off. I ended up using a wire brush + elbow grease.
If you do not have a manual, purchase the online one from cyclepedia.com I swear that is the best manual I have ever used. Every step has a nice large color picture! Why this is important is because you need to make sure you get the timing right when you put the system back together or it will be fucked up.