Does she tie? My mare hates shots, but nothing that dramatic. She tries to walk off or back out of the way and just doesn't want to stand still.
I put her in cross ties and tie them very tight. She can step one step forward and one back. She wiggles (and I have bent needles to prove it), but we get it done! Sometimes we end up doing it twice as she has bent the needles pretty badly!
I always always give her cookies as a reward. She gets one before the injection and one after.
Pinching or slapping on the area does not help. Now if you go to pat her on the neck she thinks it is a shot!