2002 Factory air ride repairs

[Siler5]

A friend of mine has an 02 with the factory air ride/leveling system. One of the shocks is leaking oil and it leans. The dealership said they have to clear the computer after the repair and the total would be like $900, I told him to wait. I was wondering if anybody here is familiar with this system and could advise me on doing the repair for him so he can save some money. Thanks in advance for any help.