The following post below describes deployment and configuration of a Forefront TMG SCOM pack to better monitor and evaluate Forefront TMG server functionality and performance.
Links:
http://www.winserverkb.com/Uwe/Forum.aspx/mom-setup/471/SCOM-Agent-Ports
http://oostdam.info/index.php/sectie-blog/249-scom-install-agent-on-forefront-tmg-server