There are a few ways to interface with C-Bus.
Depending on your switch plates, you may be able to contrel them directly with a Clipsal C-bus IR remote. You could then presumably learn the IR command and control control via the Pronto for a simple solution.
A better solution (group of solutions) would be to control via a C-bus interface. There are serial, USB and ethernet (usually called CNI = C-Bus network Interface) type interfaces available, allowing you to connect a PC or computer network directly to your C-Bus control network. You then have a number of options.
There is a private module (I believe it was developed for Qualifi in Aus) allowing a single Pronto Module to connect directly to a single CNI (via your wifi and ethernet network. If you have multiple Prontos, you will require multiple CNIs. When I asked, they were not keen on making it available to public, but they may share with installers or business partners.
Alternatively, you can install C-Gate on a PC which is connected to the C-Bus network via any of the above interfaces. C-Gate is a server program provided by Clipsal, which allows multiple network devices/programs/processes to interact and query, acting as a type of "middle man" between all other devices and the C-bus network. I gather Clipsal prefer third party software/hardware to communicate this way as it stops the C-gate network getting flooded with traffic. I use the C-Gate gate server (attached to a single CNI) to allow control via multiple Prontos.
C-Gate, C-Bus documentation & the C-Bus Toolkit are all available free online from the Clipsal website. Also have a look at the C-Bus forums for info. If you get hold of an interface, install C-Gate & Toolkit and scan your network, and read the introductory docs, you can pretty quickly get an idea how C-bus works, control C-Bus elements directly and re-program anything. There's even an introduction on how to communicate with the C-Gate service via telnet command line.
I used this as the basis to write my own C-Bus C-Gate modules, which I currently use for controlling lighting (and ducted vaccuum since the built in control wires died). My version is relatively generic but if you understand C-Gate you can use it to send and receive pretty much anything you want. If you want, you can have look here -
[Link: rohansplace.com]Good Luck