adding printer in the HP printer list

Hi There, first off i'd like to mention i have no working knowledge of OS X. i'm been trying for the last week or so to add a networked HP color LJ4700 on 8 OS X based Macs. the protocol is IP printing. the problem is when i try to add the 4700 in the HP printer list it doesnt not show up. i downloaded a DMG file from the HP page and it mounts it becasue i see it on the desktop. when i double click it it looks like its installing but when i go back to choose the driver in the list its not there. i tried selected the Other option and pointing it to the DMG file but still no go. i can select the Generic Post Script driver and it prints but the users insist on using the HP based driver because it might have some Fonts issue. from all these 8 users none of them know what to do either which to me is surprising given that they claim to have been working with Macs for years. i think they just find it amusing watching me cringe in frustration when everything else i try works. just like the Mac ads making fun of poor mr PC. anyway please help this....please help