How to set up a guest network on FIOS.

I have the following:

FIOS with the standard FIOS-supplied Actiontech router. It is doing the "Routering" as the DHCP server. The wifi is turned off.

I have a brand new Time Capsule (Airport Extreme plus hard drive in one unit) that is connected by ethernet to the Actiontech. It is providing our wifi. It is (necessarily, I am told) set to Bridge mode, which prevents the guest network feature of that device from functioning.

I have an older Airport Extreme (no hard drive) that is not connected to anything but could be if it helps.

I want to set up a guest network that will not grant access to my local network, just to the internet. Since the Time Capsule can only do this when it, itself, is the DHCP server, that route is closed to me. I was wondering if I could set up the older Airport Extreme in some fashion that would allow it to be a guest network.