Instructions
Navigate to the PlayStation Store, then to "Add-Ons," then search for "Warhawk." Purchase and download the "Fallen Star" add-on. Return to the XMB and install Fallen Star.
Launch "Warhawk," either from disc or download format. Make sure the game is updated to 1.5, then open up the server browser. Official servers that use the jetpack have the suffix "-FS" or "-ALL" for all of the expansions. The Fallen Star logo appears when a map is loading to show that that particular map uses that special item.
Look for areas on your mini-map marking the jetpack dispensers; the icon is shaped like a double-barreled jetpack. Make sure the generator has dispensed a jetpack, as you can be idled for a few seconds waiting for a jetpack to respawn, making you vulnerable to kills.