If you are installing EVP Office via a script, the easiest way is to use the EVP Office MSI, available from the Download page. It allows all the standard msiexec flags.
Running the MSI itself will install quietly, but show a progress bar, the same as running msiexec /i "EVP Office X.Y.Z.msi".)
Running msiexec /i /qn "EVP Office X.Y.Z.msi" will install the applications completely silently.
To uninstall completely silently, run msiexec /x /qn "EVP Office X.Y.Z.msi". If you don’t want to reference the original MSI file in the uninstall, you can run Get-WmiObject -Query "SELECT * FROM Win32_Product WHERE Name='EVP Office'" in PowerShell, and then run msi /x /qn "{IdentifyingNumber}".