From what i've heard its hardware that does the auto boot. i've been an R4 user for about a year and i know most of its functions, how to hack some things on it, and many more and i can tell you, you cant remove the autoboot. if you want a flashcart that doesnt autoboot, try EZ V, or AK2. to cut it short, no.
i think i've said enough. i also think now that its been answered this topic can be closed.