How to mimic hotspot?

I funnel all of my free hotspot traffic to an external Squid server using a simple Nat rule for port 80 traffic.

What I would like to do is show a splash page to new users as well as users who have been idle for more than an hour. This splash page is probably too heavy for the built in web server. Is there any way to mimic the hotspot splash page using scripting or firewall rules? Can I avoid using the hotspot package?


Thanks in advance.