Just plug your basestation into your hub. That should be it. Your Mac will dhcp from your router (assuming that's what you're doing now). The base station is basically acting like a bridge at this point. It may have router functionality, but I don't know if it will have all the features of your current router (firewall, NAT, etc).
I have a similar setup here, but with different base stations (no airport) and it works perfectly.
One thing. I don't know if the airport base station will act as a router or switch. If it does not (i.e. it's acting like a real bridge), then because you have it hooked into a hub, all traffic on your network will be broadcast by the base station. This probably is not desireable. If it acts as a router or switch, then it will only forward packets destined to any wireless devices connected to it. If it's acting as a bridge, then you may want to replace your hub with a switch (5 port switches are barely more expensive than hubs these days, so the price is usually not a big deal).