cups, filters and queue

[tino]

hi,
i'm implementing a billing system to make a self-service printing system.
i'm using a perl filter to get page size, printing quality and page number from .ps files. is it possible to filter jobs also with a paused class? i wanted to pause the printer, then filter all jobs sent by the client, so i can tell him the total cost to print all pages and then re-enable the printer to print all togheter.
i see that a job is accepted but not processed if the printer is stopped, there is any way to do this?

thanks,
tino