I use the short needles, so as long as I have enough skin to tent, and make sure the needle only goes under the skin, avoiding going 'in' to the muscle, Frog never even notices the shot. (I just shoot sideways into the tent so it can't hit anything vital, but Frog LOVES his belly rubbed and handled, that might be why he doesn't mind)
When I first started, we used the ruff (per the vet of course) and I was having a lot of trouble, he didn't like it, was a huge fight to keep him still..... now..... he only balks for the ear pokes, doesn't notice or care about the actual shot except occasionally to 'ask' for it (usually when I'm running a bit late or had to skip... he lets me know)
ETA: Eliz, it actually even says on that page, that insulin absorption is more rapid from the abdomen than from the flank, that was why I decided to rotate around both sides flank. I'm guessing it is related to the presence of more blood in that area. The important thing is the rotation, not so much the exact location... if you shoot the exact same spot always it can develop scarring which leads to absorption issues. One other thing I've noticed, the 'closer to front' flank shots are much harder if the kitty is at all dehydrated, so something to watch for I guess.