save dialog when installing an add-in
 

When an add-in is installed, a dialog pops up which asks the user whether he wants to save the add-in to his personal add-in folder:
'Copy 'MyAddIn.xla' to the Addins folder for UserName?'
I have written an add-in used by all employees of our company which is frequently updated, and I would therefore certainly not want the users to copy it to their personal addins folder, since the updates will have no effect then. Is there a way to circumvent this dialog? I have tried disabling alerts in the AddInInstall event, but it fires too late.