I've only managed to do this a few times while conscious and that's usually a few a few days of abstinence, because then my dick just gets hard and leaks precum at the slightes touch (brushing against my thigh) them some really stimulating thoughts and a bit of tension can push me over the edge..
Its not that hard. I usually manage with some nipple play and meditative kegel excercises. I would watch out for losing some stamina in the sheets, though. I find myself losing control a little quicker if I've been on a handsfree bender.