Did you create an .MSP for your Office 2010 installation using the Microsoft Office Customization Tool (setup.exe /admin)?
Inside of the customization tool you can specify your MAK product key and under the "Add installations and run programs" section you can add the script to activate it during install (attaching screenshot).
Once you build and save your .MSP file just place it under the \Updates folder and it will automatically reference the .MSP when you run setup.exe.
That's the way I do it on the template, and then the users won't get prompted to activate it.
More info: http://technet.microsoft.com/en-us/library/cc179132(office.14)