HP 5400 - web based auth - allow surfing webiste before authenticating

[cc_pr]

Hi, 
I'm setting up a web based authentication for my HP procurve 5406
I did all the steps in the manual and it works flawlessly, using the radius authentication with my active directory credendtials.

Now my question is how to allow the communication of a not yet authenticated client to certain ip addresses..

As soon as i connect a computer to the net, it gets an ip address from the switch itself and it displays the login form.
I would like my users to be able to reach certain services, such as the domain controller before attempting to authenticate, but in the documentation there are no reference regarding this possibility.

Because of that, if a active directory password has expired, the users will not be able to connect to the network to change the password, because the radius server would not grant him the access.

Can anybody help?