Having worked on my M&P's (original,shield, and 2.0) pretty extensively I can tell you that, without some kind of frame mod that would likely bypass one or more of the safeties, there is no adjustment with factory parts that can do anything about pre-travel. as stated by others, you can adjust the trigger bar loop to engage the sear sooner but then you will have massive amounts of over travel and the timing for the striker block safety could get screwed up causing light strikes when the striker glances off of the block.
the Apex FSS kit when properly installed removes all but a tiny bit of the take up and almost no over travel because of completely re-designed sear and trigger geometry but it sounds like that's not an option. Sorry man