Only on my side, my knees pulled up to my chest...
Oh, and I left out the most interesting one I had. I was 4 and a half, and my Mum had taken me to the Dr. because she was having difficulty getting me toilet trained. For the bulk of my exam I was laying peacefully on my back on my mum's lap, my shorts and underpants having been removed, however for the Grand Finale, Mum hooked an arm under my knees, and pulled them back to my chest, my butt hanging out in mid air, and the doctor did a little exploratory of my butthole; I was screaming at the top of my lungs, and fighting and struggling to evade the invader which felt ever so large as it slipped slowly inside me. But Mum's iron grip held fast. Once he was finished, and slid it back out, I was still boiling with rage, but calmed down some (that is stopped the screaming) settling into a continuous wail. That was the only time that the doctor did that to me during childhood. So, AJF, 6 is not too young to 'get it'. (It was shortly after that that I was started on enemas; interesting coincidence, eh?)
Since then, I have only had my prostate checked at my annual physical starting when I was 50, and those are the ones I receive while laying on my side, knees pulled towards my chest, the doctor sliding his well lubricated, gloved finger up my anus. I have yet to be placed in the stirrups. I dread them a little, it doesn't arouse me. I have noticed, though, that he has a sly little grin on his face after it is over...