This bassline uses 'double stops' and 'dead notes'. So please mark that in the main groove the third and fourth open string notes are dead notes (normally marked by x) and on the fourth count a double stop is played (check out the 2nd bassline). Also in the eighth measure I play double stops.
Use some hammer-ons and pull-offs in the break-sections (measure 4 and 8).
Play this groove until it's in your fingers and than improve the speed. I hope you enjoy playing it as much as I do.

ROnnie