Als, this isn´t so difficult.. In case the difference between a "Old injectors" and FSI (direct injector) is just voltage working... m very interested on working with TFSI engines.... I suppose you just need to build an electronic oscilator with rectifier to "transform" 12Volts to 70 volts (I believe this is the volatge necessary to drive a FSI injector)... After this stage a good Darlinton transistor driver between Motec Ecu signal and FSI Injectors.
This would work same as Ignition module, but with More voltage !... Do you know what I mean?
PS.. This is just my idea !
Cheers !!!