I have one and like that it sounds just nasty, go all the way back on the reed and it has a lot of attitude and rasp, put your teeth up front, roll the tongue and you have that shrill bird in distress.
Work the middle and you can incorporate the rasp as well as the higher pitched more shrill screams.
Remember, you're trying to sound like something in pain and dying, the object is to sound messed up.
I will try and cut a video on it for you though, will probably have to be tomorrow as I am home for the holidays and others in the house wont like the noise.