At the top of this page, under Useful Links, you will see a link for Product Documentation. You have to choose your IntruShield product and version from the dropdowns.
Product Documentation: https://mysupport.mcafee.com/Eservice/productdocuments.aspx?strPage=2
Response ports don't get a lot of use, but the main reason to use the response port is to interject a reset onto the network for a TCP flow.
If you are running the sensor ports in SPAN mode, you can use the response port to inject a TCP reset to the source of the attack. You'd configure the individual alert to send the reset, and then the "configure ports" GUI to setup the response port.