Different domain for ess.do

Here is my problem, I want to have a different domain pointed to the ess.do portal.

For example, if a user goes to support.example.com, I want them to go to SM.example.com/ess.do page to create their ticket.

I do not want to change the operators portal (SM.example.com/index.do), since it works fine for us. I can understand that DNS to URL redirection is not an option but is there anything in Tomcat/IIS which I can use to solve this problem?

Thanks.