How do you use .tpf (TexMod) files with Madden 08?
TexMod is a simple executable that can be found by searching Google for "Texmod."
What it does is replace a graphic that the game's programming is expecting to be at a particular memory address with a custom graphic.
If you download it and open up texmod.exe you will see that it is self-explanatory.
(While in Package Mode) at the top select "mainapp.exe", and then browse for the .tpf files, and hit "Run."