If you are using the official 2.5 alpha 2 from the blender.org website, then they do not exist. They had not been coded in at that point in time.
The texture face buttons have since been added in the SVN. You can either wait for the official 2.5x beta release (which is scheduled to occur in a week or so from what I understand) or you can use a recent SVN build from www.graphicall.org . I use the builds from graphicall and find them quite stable for my purposes.
Using the texture face options in 2.5 is pretty much identical to 2.49b. Select the object, Tab into edit mode, press the U Key to UV unwrap the mesh, then the options become available in the Object Data section of the buttons window. You must be in “Blender Game” render engine mode. The buttons will not display in “Blender Render” render engine mode.