Unfortunately, firewalls are not supported by Campus Manager since they do not support CDP. This means that UT will not be able to use them for obtaining ARP data.
What I have done as a workaround in my lab is to create a shadow router which sits next to the firewall. This router isn't really routing. All it does is collect ARP entries, and sends ICMP redirects for the firewall. All of the hosts on that VLAN point to the shadow router for routing, but are really routed by the firewall. It's not the prettiest workaround, but it will allow you to see layer 3 information in UT.
I use an old 2500, but any support Cisco router will work.