Flatten your tongue.
Place the tip of your tongue about a half inch behind your upper teeth, try to touch your upper teeth on either side with the sides of your tongue.
You want to get metal "vocal fry" (there are youtube videos) the idea is you make a continuous sound out of your throat and pull the muscle at the base of your tongue inward toward the back of the throat as much as you can.
Try not to use the whole range of movement of your mouth when you talk, stick to just moving your lips and the tip of your tongue. Try to keep your mouth relatively closed.
The overall idea is you are channeling a relatively loud sound through a relatively small opening.
Also, last day of Ennie voting:
Best Electronic Book
Mike Evans is up with Hubris
Jez (Red & Pleasant Land) and James Grognardia are up for 'The Cursed Chateau'
Best Free Product
'Santa is Dead' by In Search Of Games, is up.
Product of the Year