I have found that adjusting valves with the engine running is easier. It does make a mess though. Tighten down the rocker until it just quits clacking, then tighten about another half turn to preload the lifter. I tried adjusting by Edelbrock's instructions, but couldn't get the engine to run smooth.
I've always had good luck using this method. First off, I set the valves hot, and using a remote switch, one cylinder at at time, tap the motor around and set the intake when the exhaust valve starts to open and the exhuast valve when the intake starts to close. I've used this method for more years than I care to think about.....only my $.02