Not the solution you're looking for but hopefully this will get you on your way.
This is hardcoded into the code of qv-user-manager.
You'll need to get the code from https://github.com/braathen/qv-user-manager and make the change yourself. Unfortunately, if you're running v10SR2 or higher it is not compatible. There's a thread on how to make it compatible here: http://community.qlik.com/thread/41798 . That's where I'm at now.
I find that qv-user-manager is great but is very limited to the things you can do. More options should be available,
- # of days before considered inactive
- type of CAL you want to remove (named or doc)
- user(s) you want to remove
- document(s) you want to remove the user(s) from