yes, you put a GM PVC in the hole like normal. Then cut the hose to make room for a check valve. The trick with the check valve is that it has to be rated for the amount of pressure you're going to put to it (so it doesn't blow apart) and most importantly, it has to have a near 0 cracking pressure. What that means is that it needs to open at any vacuum level, and it has to be as invisible as possible to the airstream. That way the PCV gets protected yet the fueling won't get all messed up.
If you're clogged with carbon (which is common on the EGR tower, pushing up on the UFO will have no change. With an aftermarket chip that disables EGR it won't really matter. With an EGR chip you might end up with part throttle knock from too much timing and no cylinder dilution.
Yes, the PCV is kind of a check valve already. Its just not designed to be.... and we make it tougher on it by running more than 12 pounds of boost.