In less time than it took you to post this. You could have typed that into Google had gotton a response.
I used your question in Google.... " Has anyone came up with a way to have an in-dash USB input"
It came back with this. Not the best install, but you get the point.
Good luck! And post some pics when you get it done.
I just installed a Cobra 75wx st where my cigarette is. And just moved the lighter to a more convenient spot. Then tossed a dual USB plug into it. Since i don't use it to light cigarette's