The following is a guide to make double-clicking on a Worklist item open its associated form URL.

- Create a Form with a Worklist control.

- In the Rule Designer, add a 'When a control on the Form raises an event' Event, selecting the Worklist control and the 'Double-Clicked' method.

- Add a 'Navigate to a URL' action, specifying the 'Worklist Item URL' from the Worklist controls Data category.

See this guide to add this as a SharePoint Web Part.