As it seems, that Tasco AccuDot ist similar to my Bushnell Trophy Red Dot.
What I did, was to turn the evelation adjustment up all the way, untill it dosn`t turn anymore. That way it should be centered in the lens.
Then I started to aim high above the bulls eye of my target and just worked my self down, untill I got it centered. I pretty much centered the windage adjustment at home, so that just needed a few clicks to fit.
That was pretty much it. I sighted in my Anschütz 520 (CIL300) in on 50m.
But if you are talking about using a boresighter, I think that wouldn`t really work to well, since you would see two laser dots.
Sighting in the Red Dot took I think 15 or twenty rounds of cheap .22 ammo.
Once you sighted it in, you can then fine tune it to your normal .22 ammo.
An this is from my ammo tests yesterday. 10 rounds on each target.