Windows NT 4:
How to Install and Remove Hotfixes with HOTFIX.EXE
http://support.microsoft.com/support/kb/articles/Q184/3/05.asp
ftp://ftp.microsoft.com/bussys/utilities/hotfix

Windows 2000:
Windows 2000 Hotfix.exe Description and Command-Line Switches
http://support.microsoft.com/support/kb/articles/Q262/8/41.asp