Are all of the users going to have a login script? If they are, you can update with the net user command.....
I believe the command would be:
net user username /scriptpath:login.bat
If you dump all of the user names to a text file, you could do something like:
for %%i in file.txt net user %%i /scriptpath:login.bat
That is from memory.... I can check the files at work tomorrow, I have done somthing similar to this using the net user command....
Or you could multiple select every one in the domain in user manager and set the login script for all of them at once. That might take a while depending on how many users you have......
If you had just a few people with different login scripts and you know who those people are, it might be easier to set everyone to the generic script then switch the "special" users back....