Since cylinders 1 and 6 are companion cylinders, just watch the valves on #6 while turning the engine backwards with the alternator nut. When the the exhaust just closes and intake just starts to open, you're just slightly past TDC of #1, so put a magic marker stipe across the harmonic blancer that you can align with the fan nut or other reference mark.
Adjust #1 intake and exhaust #2 intake, #3 exhaust, #4 intake, #5 exhaust (note both on #1 then every next cylinder is intake then exhaust, then intake, then exhaust)
Rotate the engine 360degrees using the magic marker stipe on the harmonic balancer. Adjust #6 intake and exhaust, then #5 intake, #4 exhaust, #3 intake, #2 exhaust (note again, both intake and exhaust on the "end of block" cylinder, then every other cylinder alternates intake, exhaust)
In the future, just align your mark and see if #1 or #6 push rods are loose and do that series of rockers, then rotate 360deg and do the other series.
Don't forget, this is supposed to be done on a "cool" engine. Stone cold is good, manual says less than 140 degrees is I remember correctly.
This method is quick, easy, doesn't require a barring tool, and nothing has to come off except the valve cover. I usually set mine at .008 intake and .018 exhaust - the middle of the road kinda thing.