Accessing built-in textures?

Is it possible to make an ImageInformation out of in-game built-in textures? (I tried to understand how to do this by myself, but I failed so far).

I see at least 2 scenarios:

1) Displaying the texture as it is (i.e. a simple, flat square) in a GuiImage object

2) Attaching the texture to a custom 3D model. I can imagine UV mapping would be tricky, but it would be useful to ensure the model has the same look of related 'native' objects.

Thanks for the reply. I suspected this when I noticed that the textures are client-side and not server-side, so some server -> client protocol is required to display them in the client from a script on the server, file names are not enough.

Crossing fingers...