Let me see if I remember my high school biology here...

I think if you put them in a brown paper bag, they will ripen quicker.
I seem to remember that the skins of fruits give off methane which acts
as a ripening catalyst for other fruits. The paper bag traps the
methane while allowing them to breath a bit. Warmth (such as a
windowsill) speeds the process.

Leaving them on the vine? Maybe try a brown garden recycling bag at
night? Would protect against frost at least.

Or, I'm just talking out of my backside