Whenever there is no available pattern just start from the middle and work your way outward in a criss-cross pattern. To torque pan bolts without a torque wrench, use a 3/8" drive ratchet and grab it with one hand wrapped around the head of the ratchet. Run them all up snug in the criss-cross pattern. Now do it again, getting them tighter, then once more almost as tight as you can with one hand still wrapped around the head of the ratchet. This will limit the amount of torque you can apply and still get them tight enough. If you are a big strong bruiser, use your weak hand.
Joe