There are two methods in which you may allow access to a site.  Let's use www.photo.net as an example.

Option 1

You may remove any URL from the filter locally (everyone) from the 8e6 library.
From the GUI in the R3000, click on the 'Library' button at the top of the screen.
Click on 'Library Lookup' in the left-side menu.
Type the complete URL into the URL field, for example, www.photo.net
You will see of categories in which the URL is listed.  To remove the URL from the library:
Simply click on the URL line item in the search return window and click on the Remove button
Click on Reload Library

Option 2

You may create a custom category(for special access) by adding the URL in question.
Click on the 'Library' button at the top of the screen. 
Expand 'Category Groups'.
Click on 'Custom Category' group and go down to 'Add Category' option.
Type in the description and short name (less then 7 characters) of your category and click 'Apply'
Navigate your way back to the custom category group, expland the group.
Click on the custom category that you have just added.
Select URL option from the drop down menu.
Type the URL into the URL field or a wild card. Examples:

*.photo.net
http://www.photo.net

Click on 'Add' and 'Apply action' and reload library (wait 5 min for reload)
Now go to Group tab in the GUI, navigate to the group or user (Global, IP Group, or LDAP) you want to allow this category and its content for, modify group profile by locating the custom category within the custom category group and setting the category as 'Allowed'.