Do you already have the mount and power connector, and only need a place to connect the wires? If so, you can use a simple electrical connection kit Harley sells to provide a switched source or a constant on source, your choice. I strongly recommend only using a switched source however. Take a look at the harness at this link:
https://www.harley-davidson.com/store/electrical-connection-upgrade-kitThe harness basically attaches at the connector for the data port (digital technician connection) and you connect your accessory's power and ground wires to the other end of the small connection harness by splicing, either with the connectors from the kit or by soldering and shrink wrapping, your choice. There are three wires, one for ground and then two for power, one is switched and one is not.
I've attached a pdf of the instructions, you can also find them on that linked page under the "More Information" tab.
Jerry