Putting a regulator on my bottle

[RostokMcSpoons]

So I've been running with a small bottle for my Tippmann, with no regulator as it does all the clever stuff stepping down the pressure within it's own system.

Now I've got an airtac adapter for my vfc, I've got to fit the regulator I bought a while ago.  

I could just connect the bottle and fire a gazillion shots on the Tippmann, until it's empty, but that seems like some unnecessary wear and tear on the gun. 

Is there an easy way to release the pressure?

And any handy hints on fitting the regulator?