I found this "guide" to help explain "grips"
http://xeonxyh.blogspot.com/2008/08/razer-mouse-guideergonomics-guide.html
and another
I currently use the Razer Boomslang 2007 CE
and I use the "palm" grip with index finger on M1, middle on Mwheel, ring finger on M3, thumb on M4, and, if needed, pinky on M5.