Well thanks for checking on the 3 point install instructions. Maybe if I start a new thread about this, perhaps someone will see and respond.
Your issue with the power plug connection for the horn should not be to hard to overcome. I have two possible electrical schematics from the 110 tech manual. One schematic breaks at serial number 311032 and down. The other breaks at 311033 and up. Looks like different connector clips for the different serial number breaks. Also these schematics show other plug-in connectors that are within the same electrical loom. That being said, the horn connector splices in with the loom and draws power as all other connectors do off the same loom regardless of the different style connectors. The different style connectors will be do to the serial number break. I am new to the site so not yet up and running on scan and post, but will work on it if it will help.