semi stupid, bitterly sarcastic answer. I can say that we don't use torque wrenches when we're servicing the regulators for school and have never had a problem... Nor have I on my personal regs. Same with tank valve installations, the highly technical term "snug" is used quite a bit there too. Cant say I've ever seen the guys vipping my tanks use a torque wrench, and haven't seen the reg repair guys that we work with use them either *outside of dive shops, they all do in the shops because of liability*. Just take a normal allen key and snug it. They told us in the repair class that you're supposed to use them, but it's not a big deal if you don't. They are more concerned with them being too tight and mucking up the threads than being not tight enough. Same with the port plugs and hoses, you're supposed to use torque wrenches on those, but I've never seen anyone use one before outside of the official "class".
I'm certified in Apeks, and my service manual says
"20 ft lbs or until it meets the body metal to metal" for the caps
12 ft lbs or until it meets the body metal to metal for the Turret Retaining Bolt and DIN Connector
and 25 +-2 in lbs or until it meets the body metal to metal for the port plugs or male end of hose
That's what we were taught in the repair class as well. If you have access to a torque wrench, great, use it. If not, don't go wrenching stuff down. Our instructor said they put the or until it meets the body bit in because they realize that when you are out diving you probably won't have a torque wrench just laying around for you.