Controlling the un-installer flow

Is there a way to perform some actions during the uninstallation flow based on user’s input?
For example: I have to take a decision of whether to delete a directory or to retain it based on user’s input during the uninstallation.

How can I prompt a user during uninstallation?
How can I perform some actions in the uninstall flow? I know that, we can perform some actions during installation using addOperation, but how to do it during uninstallation?
Can anyone help me with a simple script (a very basic one), which will prompt the user during uninstallation and then delete a directory if he says YES, otherwise retain it (for example: /home/username/deleteme).