Barelstroker basically laid it out the same way Horus does.
So Strelok doesn't support Horus reticles, pretty sure they're not the only one either. You'll want the Horus app too, at least it's free, easy to use and it looks like it works. It'll make doing all that shit easier. You'll definitely wanna watch those videos though, there are a few of them.
It's actually pretty simple once you know what you're doing.