pam gnome-screensaver advice request

[Skunk Worx <skunkworx verizon net>]

Goal:
-----
When using gnome-screensaver I would like a simple unlock dialog that 
prompts for both the user name and password. It should not show the 
current user name. If the (user,pair) authenticates, the current user 
desktop is unlocked and the applications are again visible. The unlock 
(user,password) pair need not be the owner of the desktop.

Background:
-----------
I am creating an information kiosk.

On power-up it auto-starts a number of graphical applications. It then 
locks the screen with gnome-screensaver.

There exists a set of (user,password) pairs that should be able to 
unlock the screen and see the currently running applications.

After one user authenticates with their (user, password) pair, the user 
locks the screen with either the lock command or due to a screensaver 
timeout.

Another user can then walk up to the kiosk, unlock the screen with their 
specific (user,password) pair, check the system status, and then leave.

Continue with other (user,password) pairs as necessary.

Current Status :
----------------
It looks like Fedora 7 will be the basic platform. I am using FC6 for now.

Auto-login, starting the apps, locking and unlocking the screen with the 
auto-start (user,password) are all working.

However the dialog that pops up to unlock the screen shows the 
auto-login user name and prompts for a password.

So far I have tried adding "user1" and "user2" using the -o option to 
useradd (giving them the same UID/GID as the auto-start account) and 
then setting "user_switch_enabled" for gnome-screensaver.

Unfortunately this is not enough:

1) Actually switching users only shows "other UID" users in the 
selection list, not the "sibling UID users".

2) Switching to a "other UID" user creates a new Desktop for the other 
UID, which is as expected, but not desired. Useful for testing though.

3) Switching users again from an "other UID" shows all the "sibling UID" 
 accounts in the list. Selecting one of the users (but not the 
auto-login user) gets to the auto-login desktop configuration without 
the auto started applications visible.

It appears I will have to modify the gnome-screensaver-dialog and 
possibly pam to get this to work.

Before continuing I thought I would ask here for advice or suggestions.

Thanks,
John