Variable And Uninstall

How can I set a variable during install and use this value in uninstall?

The problem is, that the user can set the name of a service in an install dialog. But in uninstall the name of this service is unknown. So I have to save the name in uninstall. But how?

save it in the registry or a .ini, then read the saved name in the uninstaller

OK. Thank you.