Eclipse DLTK: Adding wizards to the 'New' menu of ScriptExplorerPart

Question

I'm trying to add a wizard entry to a ScriptExplorerPart of the Dynamic Languages ToolKit for Eclipse.

The wizards are accessible from File->New->Other..., so at least I know they work. They are added using the extension point org.eclipse.ui.newWizards. What I would like is to have them added as indicated on this screenshot.

To start with I figured it should probably be done using the extension point org.eclipse.ui.navigator.navigatorContent, as suggested in this eclipse newslist. This does not work however, as it seems like DLTK does not honor that extension point.

So, if anyone could point me in the right direction with regards to the correct extension point to use, or if there is another (better) way to add wizard shortcuts, I would much appreciate it.