HPD is on the Clark County SNACC system which is a Motorola 800 MHz trunked system. It affords them easy mutual aid opportunities with many agencies except the LVMPD which is a bit more difficult to do but has been done in the past. You might visit AES and pick up a copy of the 2007 Southern Nevada Scanner Book which will enlighten you on monitoring in the greater Las Vegas area.
Back in 1998 HPD joined the SNACC system leaving their VHF system behind.
AES in case you are not aware of, is Amateur Electronics Supply located on Polaris, North of Tropicana in the SW LV area. They do carry the book that I mentioned and a lot of other radio accessories.
