Ah, yes I remember now that I've done something like this in a few drivers long time ago in the first CB-Emu versions (in MAME 0.175).
But this method of manipulating m_inputs[i]->read() is quite complicated - I believe I've asked you at that time, why there isn't an easy method to send values to an ioport, and IIRC your answer was, that this would make cheating easy, and so the MAME team decided to not implement it.

Ok, I'll try it, but I'm not sure if I'll get this method working again after so many years ...