Wow, interesting thread!
The autos will be on their own internal clock, and I don't think any lighting changes will do anything.
However... MAYBE... if you increase everything that makes them grow, they will grow faster, and maybe their lifecycle will speed up a bit. So... put the light at the max, feed to the max of nutrients (w/o burn), give them a drench of maybe water soluble potassium sulfate, and possibly some water soluble fulvic acid. Make sure they are getting enough P & K. Maybe add some CO2 if possible... you can DIY a gallon jug of apple juice w/ some brewing yeast and an airlock... it will pump out CO2. (I think)
Autos don't care about 12/12 or any lighting schedule like that. So, you could run lights 24 hours.
OR THE OPPOSITE... stressing them out might cause them to finish sooner. I'd have to think hard about what "stressing out" would translate to.
I'm just throwing out total guesses here, as I don't grow autos, and I sure haven't tried to speed up an auto