How to create spherical navigation?

Is there anyway to modify the inbuilt navigation system, such that it functions on the surface of a sphere (planet)? The inbuilt system assumes that the global y axis is upwards, so I would have to be able to modify the up axis at any given point to be the vector between the center of the sphere and the given point. Is this possible and how?

Hello,

I found this tutorial on youtube, I hope it is what you are looking for.

regards

Its pretty old question, but still actual. So I implemented NavMesh navigation on sphere, you can see how it works on [this video][1], and find a [2] to detailed how-to in videos description.