I totally feel ya, Robin. I tried everything from braining a f/p pinkie to smearing the brains on a live one to actually braiding a live one (and no, I will never be the same after that experience), as well as all the other methods out there.
This might sound awful, but it's nice to know I'm not the only one with a super placid corn that actually seems scared of pinkies.
Anyway, my snake is 6 months old now, so I understand the ongoing frustration. I do have advice with force feeding though that might make it a lot easier.
1) Use Pinkies, which obviously you're doing.
2) always do it in a quiet room with as little noise and movement around you (ie; your empty bedroom with no music and the door closed). And no cats or other pets lurking around.
4) this is the tough one, but after trying to force him with a second pair of hands, I actually found this easier. Do it alone.
5)Hold his head firmly with your index and middle finger on top and your thumb underneath. His head should be at a right angle and your bottom two fingers should hold him tight. When you get the Pinky in or when he's just fed up with situation, he'll wrap his tail around his head and your hand. Trap his tail between your knees or thighs. It will get loose, but not in time to interfere.
6) Pick the Pinky up with a good grip using tongs, or your fingers (remember youre holdin him, so the whole theory about not getting your scent on his food, is already out the window). Now gently push the pinkie's nose against the sides of his mouth, back and forth. He WILL dislocate his jaw eventually. When he does push the Pinky in until it hooks onto his teeth. This buys you time to grab a narrow blunt object (tongs or a blunt chopstick). Don't shove the pinkie down in a straight line. Try to get it past his jaw by alternating pushing it in on either side of his mouth like he would do on his own. Believe me, it gets down so much easier and he's less likely to push it up. Once it's past the jaw, use your holding hand to make sure he won't crinkle up to push it out, and then push that sucker straight down at least an inch.
4) then let him go. Perferably on your bed. Give him space. I find confining him in a tub freaks him out even more.
He'll do the rest. Watch that it's going down and not up. If you didn't get it down far enough he may expel it. Try to catch it before it comes all the way out, and push it down again.
If it comes all the way out, leave him alone and try again later.
Hope this helps.
My record is 4 minutes. And he still likes to be handled, so he's obviously not that traumatized.