Are there any detailed install instructions for installing this on the main lugs and does it come with the hardware to do that?

You can "Direct Bus" connect, but you need "crimp lugs" and "keps nuts" which are not included. The instructions are downloadable above.

For a single-phase, 120/240 3-wire application, connect the two HEPD black wires to an appropriate 2-pole circuit breaker within the panel. For a single-phase, 120 2-wire application, connect the two HEPD black wires together to an appropriate single pole circuit breaker. Connect the white wire to the neutral bar, the ground wire to the ground bar (see figure 2). NOTE: We recommend this device be installed with a maximum 20 A, 2-pole (120/240 V) or single pole (120 V) circuit breaker. Keep conductor length as short as possible with no sharp bends and as close to the main breaker or main lugs as possible. Refer to 89291-0201A available on internet. Regards, Customer Care