We have been doing that for 2 years now with great success. I believe Dr Drift also has the equipment to do this as well.
We recently completed an Auto R33 GTS-t with one of our ROM tune ECU's and the car absolutely flies. Our ROM tunes are made in exactly the same fashion that companies like Mines and Amuse do so with they're ROM's. The biggest difference being that ours are tuned to Australian fuel and not Japanese fuel.
PM me if you're interested in pricing. Please insure you list EVERY modification you've made to the engine though in your PM if you decide to do so.
Cheers,
Tosh