loop over all variables to change an variable property

I'm currently working on an package template for my developers.

I have build an OnValueChanged - EventHandler.  ( i use the great example from Eric Wishdal: http://social.msdn.microsoft.com/Forums/en/sqlintegrationservices/thread/a1987e67-37d1-4998-a978-9930d029455c)

But now i want to get shure that all variables in the package have the property: RaiseChangedEvent = True

I currently hang on an loop over all variables in the package.

Because i want to build this in an template i didn't know what variables the developers use in the future.

Does anyone have an example for such an loop?

greetings

selcer