I actually have used a paintball regulator on a CO2 gun. Not on a QB variant, but on a Talon SS with the CO2 adaptor.
I have an In-Line regulator. I believe the brand is Thunder Pig. I set the regulator at 800 PSI or so and got some good consistent shots with it. It also got rid of my "Snow" problem by allowing the CO2 to revert to gas before being fired.