Band-Width Limitation

Dear All, i'm using freeradius 1.1.0 . i want to use the monthly counter function of the sqlcounter module. i want to use it to calculate Band-Width not time. i modified it and it is working fine but it sends the remaining allowed bandwidth in the attribute 'Session Timeout' and the associated code of-course. what i want is to change that code !! how can i do something like that ?? thanks for your help -- regards, Amr el-Saeed