UPS installation can be complicated. To start with, the UPS is only PART of the system; just as inportant is the transfer switch.
OK, so your UPS needs to be addad to the circuit. Yours sounds small enough to easily fit into a pull box, and be hard-wired.
Larger units, which often have wheels, are commonly attached with SO cord. These cords are connected to the panel with strain-relief connectors, and hard-wired to the circuit.
For other applications -such as a means to attach a power cord to a trailer, the device used is called a "power inlet." It's kind of like a cover plate with a plug mounted in a recessed area. This allows you to push a cord cap onto it. The problem with a UPS is that these prongs will be 'hot' as long as the batteries have a charge.
The first thing to do is contact the UPS manufacturer, and find out what his reccomendations are.