It isn’t hard with the mirrors and hand-guards I have. The mirrors are Triumph from triumph of cleveland ($$$). The hand-guards are barkbuster storm 7s from revzilla.
Remove the end caps from the handlebars (3mm allen key). Put on the mirrors (they come with a plastic inner ring so that the metal clamp of the mirrors is snug ainainst the handlebar). Snug them up but don’t fully tighten.
Then, assemble the handguards. Screw them into the threaded hole that the end caps came out of. I think i just reused the bolts from the endcaps, but they come with longer bolts if needed. Snug them up but don’t tighten all the way.
Lastly, align your mirrors to where you want them. Then, tighten everything fully. I used the inside of my garage door reflected in my mirrors to get them both symmetrical. I set both mirrors to the highest point (pointing higher up the garage door than they would normally go in order to leave some adjustability after everything was snugged down). You can then fine-tune the mirrors to your liking on the road.
