You might want to check out the post I did on Carbon Fiber Air Tanks for the Lindsay Airgraver.
It has a way of using scuba tanks to refill Carbon Fiber tanks used in Paintball guns.
This way you don't need to find a primary regulator to reduce the pressure down to 1000 psi where the regulator for the CO2 tanks can handle it.
Then when your Carbon fiber tank is empty, you can refill the tank from the ( or any) scuba tank with a fitting sold by Tippman Co. for this purpose. The fitting cost about $35.
The link is here:
http://www.engravingforum.com/showthread.php?t=1809
Tim C