First I started with buying the hardware, the car the engine is in did not have DBW, and made the wire loom, then I bench tested the whole system.
The first thing I did was to run the auto calibration function, this will latch the minimum and maximum voltages of the position sensors(sensor curves).
Then its trial an error regarding the PID settings, it’s hardware related thus it will be up to you finding the best numbers. One thing that will have the most impact is the control frequency, mine worked best at 8000 Hz.
As for the help from Cosworth, when I started with this, this forum did not exist yet, but I received some help from Neel Vasavada, who owns Apex Speed Technology.
Hope this helps a bit.