I just got a CAV COMP from Brownell's.
It comes with a 5/64 pin and small hole.
this is a quote:

"For installation on a post-ban rifle.
With a hand drill, use the hole in the bottom of the comp to guide a 5/64th drill bit no more than 1/16th of an inch into the barrel. Drive the enclosed roll pin completely into the hole to permanently affix the comp onto the barrel."

Is this enough? or do I need to weld or hi-temp silver solder?

If your barrel is threaded you have to weld it or use a high temp silver solder ( with a melting point of at least 1100 degrees F)