Not really a 'Step by Step', but here are some photos that should help clear up the poor BRP destructions.
A few things:
Make sure you are mounting the proper turn signal to the proper side. The pics should help.
You have pull on the turn signal wires while pushing them into the hole and then into the bar - you can only really fit one connector through at a time - kind of tricky - but pulling from the other end helps a ton - just had to pull a bit harder than I expected.
Hopefully the photos will help with the rest. PM me if you have any questions.