Figure out which unit you have. Out the box, the iAqualink comes in two versions for up to 8-relay models (PDA8, RS8). One for older control systems, and one for newer systems. If you have a larger system than an 8-relay unit, you will have to send your current CPU board to Jandy to upgrade (silly IMO, seems like they are worried people will upgrade their systems to higher-end models...).
Basically, all you need is an iAqualink to program/control your aqualink. You don't need a PDA or a control interface anymore, though you can use all three together at the same time. The iAqualink acts as its own, and can be used over the web in a browser or a smartphone app. Its user interface modeled after the touch control interface.