Use the following steps to accomplish this task:
• Use the Model Editor as described in the Add an Item to the Navigation Control topic. The item will be visible only if you set its View property. Specify any View there.
• Handle the ShowNavigationItemController.NavigationItemCreated or ShowNavigationItemController.ItemsInitialized event. Add new ChoiceActionItem to the required navigation group. See How to: Implement Custom Context Navigation for details.
2. Handle the ShowNavigationItemController.CustomShowNavigationItem method to execute your action when the custom item is clicked. See the example in the following topic: How to: Create a New Object using the Navigation Control. To execute your action, call its DoExecute method.
Let me know if you need further assistance.