For me updating the Access Gateway Appliances over HTTP or FTP is a bit of a hassle. Usually I am at a customer and getting access to an FTP or HTTP host is almost impossible. So normally I install vsftp on an IDP, ssh the LAG updates to the IDP and then FTP to the LAG. But this method has its own problems so I decided to use the tomcat instance that is installed on the IDP as the HTTP host.
If you are not using iptables to redirect traffic from port 80 to 8080 you must specify this when specifying the hostname as part of the upgrade script. i.e. idp:8080/nidp/lagrpms.tar.gz
Disclaimer: As with everything else at NetIQ Cool Solutions, this content is definitely not supported by NetIQ, so Customer Support will not be able to help you if it has any adverse effect on your environment. It just worked for at least one person, and perhaps it will be useful for you too. Be sure to test in a non-production environment.