Go to http://mumble.sourceforge.net/ and download "Mumble 1.2.3a (Stable). Once it is installed run the client. If "backwards mumble" installs with the regular client, do not run the client that says "backwards"
When Mumble appears on the screen you will see 2 boxes. The first box at the bottom will have a button that says "Add new" Click on that button and enter the following.
Label: South Of Heaven
Address: southofheaven.mumble.com
Port: 8153
User: (Enter your ingame character name)
Click "OK"
South Of Heaven will now appear in the favorites list on your Mumble client. Highlight the name and click on "Connect." You will be prompted to enter a password which is "Heaven"
You should be in!
*If you have any problems with this, please contact an ingame officer.