In order to replace running (being used) files, we can use the Windows MoveFileEx API. This allows the update to be made during the work hours, and after a PC/server restart, the new file will be available to use.
The below is the illustration of how to use it within a VB6 command line app.
My VB6 InUse command line app (VB6 source code, and how to develop command-line VB6 app with support for command line parameters)
Another Sample InUse file replacement code for download