If you're getting cynomel or cynoplus tablets, they have microgram dosages in each tablet/pill (25mcg of T3 in cynomel, 120mcg of T4 and 30mcg of T3 in cynoplus), so you won't need to weigh out precise amounts of powder or anything like that, if that's what you're worried about.

More generally, a common way to make dosing precise small amounts of a substance easier/safer/more consistent is to make a relatively low concentration solution in a liquid, and dose by volume.

When I wash my hair I do it first thing when I get in the shower, then I'll shake my head to get surface droplets off and try to avoid getting it wetter for the rest of the shower. Immediately after I finish showering, when the air is still really humid, I'll apply light pressure to my head with my hands and squeeze out some of the water kind of like gently squeezing out a soaked sponge. If your hair is long enough you can also grab a tuft in your hand and gently squeeze to wring it out (but don't twist or pull like you would when wringing out a towel), this is optional and just makes the next parts take less time. Then I rub my scalp vigorously with a towel for ~30sec (I probably worded this part a bit weirdly but I think this is basically the "normal" way most people dry their hair with a towel) to remove surface dampness, then wrap the towel around my head and let it passively soak up moisture. Wrapping a bit tightly so that there's mild pressure/squeezing action helps speed this along. Don't go so tight that it's uncomfortable though. Ideally you would keep the towel on until your hair doesn't feel damp to the touch, but if your hair is long and/or thick this can take quite a while, so realistically you'll probably want to get most of the way to dry this way and then do the "normal" vigorous-rub-dry again to finish up.

Basically the idea behind all of this is to slow down the rate of your hair drying out, so that it doesn't "overshoot" a good moisture equilibrium and dry out. Before I started drying like this I found my hair would usually be a bit thin and brittle for the rest of the day after showering, and it wouldn't look good until the next day after sweating in my sleep would remoisturize it. But once I adopted this drying method it would be right where I wanted it to be right away.

Going strict nopoo (no shampoo, no conditioner, no baking soda, just water) solved most of my dandruff issues on its own. So frankly I can't speak to how effective this drying technique is specifically for addressing dandruff. But for me, my dandruff was a product of the classic overdrying/overproducing vicious cycle that occurs when you strip your scalp of its natural oils with shampoo, and drying this way also helps your hair and scalp retain a healthy amount of moisture, so it stands to reason that it could be useful. Hope it helps a bit.

I've been a little curious for a while about possible benefits of topically applying progesterone to the workpiece before/during use to mimic the effect of natural lubrication. Someone braver than me should give it a go and report back