Shorewall users - Nov 2002 - Allow a PC to have access to the ''net'' according to a schedule/time table

When I was using IPCHAINS I could manage my daughter''s access to 
the Internet at specific time by inserting or deleting a REJECT 
rule for her PC IP address scheduling the running of the activation 
and deactivation script via CRON.

I would like to achieve the same result with SHOREWALL.

Any idea on how best to do it?

Thanks,

	Costantino