Captive Portal with Bridge

I'm trying to use NoCatSplash to create a captive portal on a bridge machine
that has an IP address assigned to the bridge device.  NoCatSplash uses
iptables and it seems that this is the beginning of my problems...i guess I
need to be using ebtables.

I've setup NoCatSplash before and found it rather easy to get working but am
having a hard time getting it to work on the bridge.  The idea is to be able
to very easily insert a captive portal at a bottleneck point in a given
network without reconfiguring all of the routers and access points already
installed.

My bridge setup is as follows:

ifconfig eth1 0.0.0.0
ifconfig eth2 0.0.0.0
brctl addbr br0
brctl addif br0 eth1
brctl addif br0 eth2
ifconfig eth1 up
ifconfig eth2 up
ifconfig br0 10.0.0.99 netmask 255.255.255.0 up
route add default gw 10.0.0.1

I've configured NoCatSplash to use br0 as the interface and 10.0.0.99 as the
ip address but of course its not working.  I'm not sure what i'm missing but
i've hit the limits of my knowledge...can someone help me with this?

Thanks in advance!
dennis