customize sMessage option Print button - TableTools

Sheenapatel

I have a form that allows a user to select filters. This is then displayed in a DataTable. I am using the TableTools functionality to provide the user the ability to print the table. I want to display all the selected/entered filter values in the print view. Right now I can display a string using the sMessage option but I am not sure how to get the values to print a function that retrieves all the selected/entered values. I know I could just use document.getElementId('value').value but what about if the value is null and I want to display an Unknown.
Thanks