Recently I came across a great article on publishing Exchange 2010 with TMG, I use this article in the production environment and it worked perfectly and I thought its worth having the these links at my blog.

http://rdpfiles.com/2011/08/15/publishing-exchange-2010-with-tmg/
http://rdpfiles.com/2011/08/15/publishing-exchange-2010-with-tmg-2/
http://rdpfiles.com/2011/08/15/publishing-exchange-2010-with-tmg-3/

regards,
Krishna  🙂