what about this:
Enable LAN to WAN Filter?: yes
Time of Day to Enable LAN to WAN Filter: 21:00 - 23:00
Packets(LAN to WAN) not specified will be: ACCEPT
Source IP - Port Range - Destination IP - Port Range - Protocol
192.168.1.3 1-65535 [leave this box empty] 1-65535 - tcp
just an example
otherwise you can do it by ip-tables.
http://www.cyberciti.biz/tips/iptabl...me-of-day.html
you probable need a separate rule chain for that (the chain with the computer ip's blocked)