I've aligned a few used ones to the chain with my specialty tool, channel lock pliers. No diss assembly required, and it lines up closely enough just by having your eyes open.

You do want to avoid bending the frame and having the wheel bolted in helps with that. Just grab a part that will only result in the derailleur hanger being twisted back in the right direction.

I'm not big on finesse, and apologize if this is too crude. Words I like to live by, 'close enough.'