the IAC position when in IAC-open loop is controlled via a few tables that could be messed with, but they're not in effect with a closed throttle other than cranking, immediately post-cranking and after immediately throttle closure until the closed-loop IAC control kicks in to maintain target idle speed.

it's not necessarily the greatest workaround, but moving the commanded idle speed tables around to get into the 1200 range SHOULD allow you to keep your foot off the throttle long enough and give attention elsewhere until you can get the fueling and spark roughed in. then you should be able to lower the idle to whatever speed you're looking for, or at least play with the IAC control settings to get it to react the way it needs to.