Hi,
Unfortunatelly, you cannot configure UAG with an alternate scenario on the UAG server side. UAG rely on TMG for it's own protection. On the client-side, alternate firewalls are possible if the are comparible with the Windows Filtering plateform and do not
replace Windows IPSEC tunnels Feature. In this case, you will have to configure client firewall settings in McAfee firewall configuration.
Have a nice day.
BenoitS - Simple by Design http://danstoncloud.com/blogs/simplebydesign/default.aspx