This procedure will vary hospital to hospital depending on the actual equipment you have available for transducing the pressure.
The biggest variable here will probably be what kind of transducer you have available, and what type of monitor you have.
The physician places the central venous line and ensures it is within the vein prior to anything being connected.
Then the catheter port is attached to IV tubing primed with saline, which has a stopcock on it.
Attached to this stopcock should be your transducer, and the other end of it will be attached to your computer monitoring.
It is important that this transducer stays at the level of the patient's heart, so that the CVP measurements are accurate. For example if the patient sits up in bed, then the transducer must be adjusted so that it stays at heart level. This can be done by taping it to the bed to estimate heart level, or by manually adjusting it on the IV pole whenever changes in position are made.
To get the CVP reading, the stopcock must be turned in a fashion so it is open to the venous line, and if IV fluids are being infused in this line, the stopcock must be closed to the transducer.
You will want to "prime" the circuit with normal saline, to make sure there are no air bubbles in the IV tubing.
I tried to find such images on the Internet, but I was unsuccessful, besides finding this very large manual (in PDF format):
See page 93 for the actual portion on CVP monitoring.