Karl Sanders uses rather vintage equipment, kinda surprising considering 
on 6-string guitars, but that's what they do, I've e-mailed Karl to find 
only riff I have because my pitch is not very good so I can't figure out 
stuff very well. However, when I saw them live, I watched Karl closely, 
and this is how he played the middle riff.

|-------------------------|
|-------------------------|
|-------------------------|
|-------------------------|
|-0-5-0-6-0-5-0-6-0-5-6-7-|
|-0-5-0-6-0-5-0-6-0-5-6-7-|

then the riff changes to tremolo picking as follows.

|-------------------------|
|-------------------------|
|-------------------------|
|-------------------------|
|-------------------------|
|005500660055006600556677-|

I know it's only two riffs, but I thought I should post 'em anyways.