They award them by your percentage of contribution to a raked pot. Not sure exactly how many or how fast, though. IN the month or so I was actively playing on there, I range up about 40K action points, playing mostly 100NL.
I bet the bonus would clear pretty fast at 4-8 and above limit.
"I don't think I had the nuts in that tourney at any point except when I hit quads on the river against Lindy"