These two units are in the Navy Reserves. The Navy Reserve doesn't "make" pilots, they have people who are already qualified naval aviators join the Reserves after leaving Active Duty.
So, if you want to fly with HSC-84 or 85, then you will need to get into flight school through the Naval Academy, ROTC, OCS or one of the other commissioning sources. Complete flight school and fulfill you commitment that you incur for going through flight school in the Active Duty Navy. While in flight school, you need to be selected for helos. (Not hard, but occasionally there have been guys who wanted helos, but got something else.)
When your commitment is up, you can resign from the Active Navy and apply to the Reserves. This is where you "rush" the unit like MB talked about. The squadron has a say in who joins it, so you want to make sure you are a known to the squadron so they can request you by name. They unit won't have much information on how to join it on its webpage since you transfer into those units from the Active Duty Navy (for pilots).
If you want to enlist in the Navy Reserves and get trained on a skill set that the squadron needs, then you could probably go to it without having been on active duty, but for pilots, you will usually need to be an Active Duty Navy pilot first and then transfer into the Reserves.
