I am not sure why you want to change the name but it can be done. There are a few steps that you have to do in Sketchup.
In order to change the name, you will need to 
Select the Texture for your object surface with the default texture of your choice. (The default tray is open to Materials. Have the Materials dropdown open)
Click the little cube with the plus sign. This makes the Create Material window popup (It can be found on the right side of the top panel of the Materials dropdown)
Give the material a name. Then click OK
Now paint the surface of your object
Right click on the surface that you just painted and click on Make Unique Texture
Now you can save the object as a Sketchup 2015 file and open it in 3dxchange. It should transfer your new texture names.

I am not sure this is what you are trying to do. There is probably a plugin that can do this. If I find one I will pass it along.
Craig