The thing is Sicilian isn't proper, so there really is no way of writing it. You try the best you can phonetically. To say "he" in Sicilian, you'd say, iddru. To pronounce that would be, "ee drew". So, to answer your question, if I understand you correctly, yes, it'd be the same, being that you write sicilian the way you hear it.
The poster above, Tommasso, says to spell it "iddu". No matter what, when pronouncing it in sicilian dialect, you're going to hear an "r". That's just the way it is, so I'd choose to spell it, "iddru".

And to the topic of this thread, De Niro says "Iu" meaning "I", when he should have been saying "Iddru" for "he".

My head is spinning now.