I replaced my lifelines this Spring using the kit from Catalina direct:
Catalina Direct: Lifeline Standard Kit C-22, CP-22
They have two versions, standard and deluxe. The deluxe is two pieces per side, so the front doesn't go slack when the gate is open. I went with the standard. My wife wishes I'd gone with the deluxe.
It may be a bigger pain if your boat didn't have them originally...I'm not sure if you'll have the attachment points on the pulpit or stern rail, or if there are good flat places to put the stanchions. I'd check on that stuff before buying anything, or they might know at Catalina Direct.
There are pics and stuff of mine here:
My Butyl Heart | Sailing Fortuitous