If you don't have a torque wrench that does in-lbs I would suggest using a socket driver (screw driver handle that you put sockets on the end) or a 1/4" drive socket wrench that way you aren't tempted to torque down on it like you might be with a larger socket wrench. Just snug it down and give it about a 1/4-1/2 turn. Start in the middle and work your way towards the ends of the valve cover crisscrossing side to side. Some locktite on the bolts wouldn't be a bad idea as they may loosen up on you.