|You should have created a new thread for this question.|
The quick and easy way to do this is to statically assign TCP/IP settings to the clients you don't want accessing the internet. If you don't give them a "default gateway" address, they won't be able to access the internet. With an appropriate IP and subnet mask, they'll have LAN connectivity.
Check the DHCP Scope on your router beforehand and ensure you only use IP's outside the DHCP scope to avoid possible duplicate IP's.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.