The only way you can enforce
the redirection (i.e. w/o the cooperation of the requesting computer) is to have your wireless router (or whatever is between these computers and the Internet) to do the redirection. I'm guessing that's not an option for you, but if it is, post back.
There are two ways for the requesting computers to do the redirection. One (which will work the same way on any OS) is to set up the browser(s) to use 192.168.1.1 as a proxy. One drawback to this solution is any user can change his own settings and defeat this.
The other option is to have the firewall redirect. This method will, of course, depend on the OS the computer is running. If the computer is running Linux, I believe the following rule will work.
iptables -t nat -A OUTPUT -p tcp --dport 80 -j DNAT --to-destination 192.168.1.1