I don't know how well it's gonna work with screamin vocs. It'll probably work okay if you're doing screams with pitch, kinda like Linkin Park type stuff. Use it like any other plugin with your recording software. Tell it what key & mode the song is in, and play with the faders until it sounds like you want it to. If you only want to fix parts of it, you can bring the whole vocal track into a wav editor, and apply fixes to selected parts.