Do you use an autoinjector or a needle? For a needle, I just slowly push through and that works better for me. But the medicine I use that way can be IM or subQ, so I don't really worry if I don't go all the way to the muscle.
Autoinjectors don't have that option, but it might be easier to find someone to do that for you. I give my brother his autoinjector medication. You just have to commit once it activates and keep it from coming out and leaking. Easier to do when you aren't the one experiencing it.