If you have Pro Tools 6.4 or higher, here's how you use the Click plugin in a session:

1. Create a Mono Aux Input: File - New Track - Mono Aux Input - click Create
2. Go to your Mix window: Windows - Show Mix
3. Raise the fader on the Aux track to the desired level
4. On the new Aux track, choose the top plugin button, go to Plug-in - Instrument - Click (mono)
5. Click on the metronome icon in the Transport (blue is on)
6. Here you can change the level of the accented and unaccented click
7. You can mute or unmute the track and change the level as desired