Rips I can mount an 18.2hh without stirrups from a block! I'm 5ft8 so even if you're only 5ft you should be able to do at least 16hh! It's like mounting normally, you turn to face the horses bottom, lift the right leg and swing it over the back of the horse and land in the saddle, if the horses p!sses off you have your weight centered over the mounting block and not the wobbly stirrup iron, honestly it's much safer! Henry never stood to mount when I first had him and because I wasn't fussed about him moving using that technique neither of us ever had an issue and he learned to stand like a rock.
I have though found that mounting pony from the ground, with Henry I used to scrabble up, with pony I have to really remember to get a bounce going before I put my weight in the stirrup to get up.