I’m diabetic so not IM but I’ve always had a problem with needles. A few things helped over the years, by far the most helpful thing was simply not watching; pick a spot and raise the syringe up a few inches look away and let gravity drop it home.

At times I found it helpful to use more distance or more force.

I used to do something to distract myself like literally screaming while doing it.

I used to do something like taking a few quick breaths and then holding the last one as long as possible and then doing the jab on the inhale. Or the opposite (while exhaling).

I’ve never tried this, but there was a syringe design that covered the needle in a retractable sleeve. I imagine something similar could be rigged up with paper and tape… just be careful that it slides up the barrel rather than crushing. It’s probably a good idea to test whatever design you choose on some fruit or another object before trying it yourself.

Good luck :-)