Setting the reg is real easy - but takes 10-15 mins, paint and a chrono.
Screw the Rex all the way in, then all the way out counting the number of turns it takes,
Now screw the Rex to the mid point (ie. if it's 8 turns out then go back 4 turns)
Have the Ergo adjustment screwed in (i.e. lowest pressure.) - that's the screw at the bottom of the reg
Add the air
Increase the Ergo pressure until it there is a fair amount of pressure out the barrel, enough to fire a ball out so you don't end up with 18 stuck down your barrel!
Add some paint and find a chrono.
You'll probably be shooting just under 200 now
Increase the ergo bit by bit, shooting a few shots after each adjustment to settle the regs.
You'll get to a point that the velocity levels out, i.e. increasing the Ergo doesn't increase velocity, and if you keep increasing it then the velocity will actually reduce. This is likely (alhtough not guaranteed!) to be around 270-280fps.
Reduce the Ergo back down to the lowest point you are still getting that peak FPS.
Now just use the Rex key to fine tune the velocity to what you want.
Most important things with this are having good paint so you get consistant velocities and some patience, just keep shooting at each adjustment to settle the regs down.
This will give you the best operating pressure for your particular gun, most efficient and best consistency.
I doubt I'll be at the indoor - although possibly Sunday. Best of luck mate and let us know how you get on if I don't see you.