The best suggestion I have is for you to get a copy of Dameware NT Utilities. www.dameware.com
Dameware is a NT/2K/XP administration tool that can manage all of your servers. You can add users, add machines to AD domains, look at running Services, manage Terminal Services sessions, view shared folder info, look at open files, and a whole bunch of other stuff.
One of the other features is the Export feature.
You can connect to a Domain Controller, and export the entire user database. You get all of the fields from AD Users & Computers EXCEPT for the password field!
So, I suggest you get Dameware, run an export against on of your Domain Controllers, and then open the file it makes (a .CSV that you can open in Excel), and sort it by theLogon Script column.
Bingo! Then you will have a list of all users who use the logon script you are interested in.
Dameware has a 30 day fully functional trial you can download.
And no, I don't work for them! :-)
hope this helps