Cisco GSR logging issue

i'm working with some folks to try and develop evidence about
proxy hijackers on or transiting their networks. i have useful
notes about doing this with non-GSR Cisco routers, but right
at the moment all i have for the GSRs is a note indicating that
netflow is needed. i have no personal experience with the
GSRs and am looking for one of two things:

1) someone experienced in capturing this stuff on a GSR


2) a pointer to a cisco oriented list where i can get 1) above.

thanks in advance,