I want one way, so that everyone who punches stuff has a way to punch on the move.
You have that here...
Once you are entitled to 3 attacks (11 BAB), your standard actions and attacks of opportunity can become double strikes, the first strike at your highest attack bonus, and the second at that -10.
Mis-read the first time through, hehehe. I don't see how anything else needs saying to that honestly!