Adding a warning message in initial GUI window

[pankajmjx]

I generated an msi using bdist_msi option. I am using upgrade_code which adds functionality of removing all the previous versions when an msi with same upgrade code is installed again. Currently all the previous versions are uninstalled without notifying user(without any message on GUI window). Is there a way to add a small message or text in the initial GUI window which appears on installing MSI(window which has next and cancel button)?