APEX

Hi,

I'm building several APEX Applications, and using NTLM as its Authentication Scheme. With this, the users won't have to type any user and password. And their user name stated in top right screen.
I'd like to build another application to administer users of all created APEX Applications. So I'd like to build 3 tables:
1. users (hold user name, and user data)
2. pages (hold APEX Applications pages)
3. access_list (hold combined data of users and pages and access flag)
The last table will give me an SQL that can be used to create page level Authorization Scheme.

The problem is:
I cannot find a way to get a list of user ids to pre-populated the table users. Is there a way that an administrator user use an LOV of all NTLM user instead of typing domain\user to this application? OR is there a better and elegant way to create User Access List with NTLM.

Your helps will really help me, and thanks in advance.

Regards,
Aulia