With the right tool, you should be able to remove the valve springs without removing the cams.
If you knlow your rings are bad, why bother with the valve seals before going into the einge to replace the rings?
If you think your porblem may be carboned up rings, check out Bob Is The Oil Guy, the oil and gas additive forum, and look for posts on a product called "Auto RX". Many there have posted that it will clean up fouled up ring packs.
www.bobistheoilguy.com 
