I can recall a similar conversion done in a Hilux before.
In regards to setting this up I would recommend giving GasResearch a call directly.
You can contact them on +61 (3) 9706-6322... I would probably ask for Joel, I have found him very helpful in the past.. provided he is free to chat (Being good, also makes him very popular)
They should be able to give you some good advice as to what will work, how much, etc.. based on their previous experience.
I am currently running a GasResearch setup on a 3T-GTE turbo. It is not using an ECU (has a separate system for ignition).
If you are looking at getting an aftermarket ECU the other alternative is LPG injection. This is something I am in the process of experimenting with at the moment.
You may want to speak with one of the forum members (MrShin) if you are interested in going down this path... he is currently running LPG injection on his turboed 4A-GTE.