I tried the treat thing once with Cedar, and it only proved that he is smarter than I am....
Step 1: Position horse at mounting block. Give treat.
Step 2: Step up on mounting block. Pet horse. Wait. Give treat.
Step 3: Pretend to mount, pet horse and praise. Give treat.
Step 4: Mount horse. Give treat.
Success! Not a single step, fidget or butt swing.
Pick up reins, legs lightly on, cluck.... Horse stands still as a statue.
Nudge with my seat, cluck louder, give a little pony kick.... nope, not moving, still waiting for another treat.
Finally, slap smart *ss horse on his smart *ss with my hand, kick hard and admonish with a 'git to going!"
Horse walks off as slow as possible, hoping for another treat.
Thus, we moved on to the round pen method.