Can an object listener be reached without saving it as a property?

I would like to temporarily disable one of my listener for a short period of time. Is there a way for reaching the listener object without saving it as a property (I create the listener in the object's constructor)?

Second question: I have several properties which affect the same property when modified, do I need to create a listener for each property, or is there an easier way around it?

Thanks for the help!