Some people say that you can very gently slide the cam out when you find the 'sweet spot'. I've always had to extract the opener rocker shaft (throttle side of bike only) about 1/2" - 3/4" which allows the rocker to move away from the cam lobe and gives the cam more play room. It's not necessary to pull the shaft completely out unless you need to replace the rocker.
DO NOT pull the closer shafts! Unless you need to replace a closing rocker, do not, do not, DO NOT pull the closer shafts. The closers are extremely cumbersome to get back in place and most people end up having to pull the heads to gain more access room. Pulling the heads poses another whole set of issues that you probably don't want to deal with.