HFS-3 on BMW 535d

[KertRe]

Hello!

I am from a small country called Estonia.
So i ordered myself a aquamist HFS-3 kit. I am planning to install it on my E61 535d. Right now its tuned to max with stock turbos and everything. Next logical step in my mind was water/meth kit.

I have a few questions about it. How is the injection going to be controlled? I understood that there is a possibilite to control it via fuel railpressure. It should work then with railpressure sensor? What wires i do have to connect there then? I have looked at HFS-3 diagrams, but still a bit confused. I would be very thankful if someone could draw a simple diagram etc.
Also, how or from where i should setup failsafe? And what size nozzels i should use, and 2 nozzels or install 3?

Best regards,
Kert