We used to use an inkjet printer for making film positives for our silk screen operation, so perhaps that is similar.
We used a special transparency film and special, high-opacity inks. I don't remember where we got it, but we used a modified Epson printer (wide format...something like 18" if I recall correctly) that was equipped with a high-capacity, refillable "outboard" black ink system (it had a little tube that reached down to the print head).
Anyway, the whole system was a decent try, but ultimately we abandoned it. We opted instead to outsource our film positive production to a local company that had a proper filmsetter machine. Not only was the resolution far, far superior, but the resulting films were more durable and (most importantly) water proof.
I don't know if any of that is relevant to what you are trying to do, so take it for what its worth.