Alignment operations have special treatment in Geneious. They always appear as a tab in the options for the general alignment operation and you can't change that. So for ExampleAlignmentOperation go to "Align/Assemble -> Pairwise/Multiple Align" and there will be a tab called "Padding Alignment". Are you able to see that?
If you want to write a more general purpose operation, the ExampleWorkflow is a good one to start from. It already implements getActionOptions so you can tweak that. What goes wrong when you try to run it? What operating system and IDE are you using?