looks like everyone is more concerned with the lighting system and making it work rather than get it to communicate with the Pronto. There's a lot of talk about using neutral or ground wires: This is specific to making the lighting system bus work properly with the building electrical system and has little to do with the Pronto communications.

In general the Pronto will connect to pretty well any lighting system that has either an ethernet connection or RS232 on its controller. The kicker is sending the right codes!

Regarding two way comms: Prontos can send and receive, but only the Pronto can initiate communication (open the socket). This is my personal pet peeve! Thus the Pronto supports two way comms, but the comms must be initiated by the Pronto regardless of what you want to communicate with. This can create some challenges which are sometimes resolved with a polling style of communications -or- using a just in time pull method based on page or activity entry.

If you're looking for pre-packaged stuff with ready to go scripts or xcf modules: The guys have given their recommendations above. If you are looking to do your own programming work, the same recommendations apply; it's just a question of price, functionality and availability of vendor command codes.