Yes, this is possible... if you can't use the generic messages (as linked to above), you need to create the pop up messages in your PACKAGE itself.
Though, I can't do this for you, I can describe the steps...
1) create the silent automated install (sounds like you alread have this done) Sometimes, this is performed by just adding SWITCHES to the manufactures provided executables... like /s for silent... Other times, you create you own package in something like WISE Installation Studio or the SMS installer.
2) wrap you package in WISE or the SMS installer... Here you put all of your code to complete the silent installation ; however, towards the end of the package, your create a popup message for the end user. ..you can put something like this "your computer has installed office and computer will restart in 10 minutes". Because you can created this wrapper in WISE or the SMS installer for each package, you can customize the text for each package.
3) create a package using the new package
4) advertise the package.
WISE:
http://www.wise.com/Wise/Products/Installations/WiseInstallationStudio.aspx