this is more than tricky, i'll try to explain it quickly since it can take a LOT of time: extract the contents of the installer, you'll see a .msi file. create an admin install point "msiexec.exe /a %path%\bitdefender8.msi" on the new folder containing the admin install you can edit .ini files, most of them contain preferences. add the cumulative update overwritten if necessary. now you are ready to install with /qb switch over the .msi (admin point) or you can take the whole folder and add it to a rar-sfx to save space. finally your serial is stored on win.ini, you'll need to replace it during installation