Ordering items in a combined page & posts menu bar

Fantastic theme Flynn. Makes building a simple site so much easier.

I have a menu bar that combines pages and categories (thanks to this forum post).

My menu is mostly page items, but I would love to be able to insert the category items at my leisure, rather than having to lump them all together as either 'pages' then 'categories' or vice versa.

Does anyone know of a way to do this, or a plugin that might do the trick?