You do not have to discharge your AC, just have someone hold the condenser out of the way like on Raughammers write-up.
Torque Central Cam Install Page
Raughammers Cam Install Page
The big thing is to take your time and make sure you do everything correctly. Especially putting the front cover back on...make sure the crank pulley seal is centered on the crank so you don't have an oil leak like me

It's a pain in the azz to have to go back and fix something you should have done in the 1st place.
It's really a pretty easy and straight forward install.
Good luck...