Hi,
Thank you for the post.
Before going any, there are some basic questions that need to be asked. Are you trying to using web publishing?
You may refer to the following steps to achieve your goal:
1. Create the Web publishing rule using the wizard.
2. Change the incoming web requests listener to another port such as 8080 on ISA
3. Change the web publishing rule to pass it on 8080.
4. Change the port that IIS uses on the IIS server to use port 8080.
5. Open IIS manager right click the default webpage of the server to use TCP
port 8080.
Just keep in mind with outbound HTTP access for users that HTTP is still HTTP no matter what the port. So you still use the same HTTP protocol in the Rule. The port is simply supplied in the URL. The only reason "80" is not included all the time (http://www.somesite.com:80) is just simply because it is the browser's default and so isn't required.
Regards,
Nick Gu - MSFT