Software Deployment

I am trying to install the new Symantec Enterprise Vault KVS Client 7.
I've done detailed MSI logging and see error 1603.
The install hangs up because file name valkyrie.dll is in use by outlook.exe.

Now I know that executing this msi with a /qb or /qn switch will work very nicely as long as outlook.exe is NOT running.

My problem here is this... I need to push this out to 700 users and I cant count on them closing their outlook. I need to make this install go smooth while they are possibly logged in and using outlook.

To my understanding there is an InstallValidate check in the Windows Installer that finds the locked file and force this error.

Here is my question now.
Is there a way to use Wise MSI editor to edit the msi or creating a new wsi out of the msi and then change the install around so that if a file is in use it does stop with error 1603. Instead what I would like to see happen is that the file gets written somehow to fix itself on the next reboot. I know I've seen apps that do installs and then you have to do a reboot to repair the files that were in use. I would like to do that with this msi. I know the exact file in use. This should be doable.

Thanks
Dan