NT challenge response for http%2360server5555

Hello,
We are hosting WebMethods on NT Server. Just want to know where is the security set that prompts the user with the Nt Challenge Response everytime we try to access any resource from the port 5555 (IS).
Specifically getting the NT C/R for the Web WorkflowInbox page(which is served by the IS(port 5555) is annoying…
http://<server>:5555/web/WmWfServlet/wfservlet which brings up the login page is first stopped by the NT challenge… which we want to avoid.
Any idea how to suppress it atleast for this case?
Thanks!!
Sang