Sorry no, I am not aware of any free Direct X 10 games.
However I think this might assist your project, 3D Ripper DX pulls ALL
the textures from any DirectX (6, 8, and 9) games. Part of the C++
source is included.
The author's profile page is;
http://www.deep-shadows.com/hax/
The program page is;
http://www.deep-shadows.com/hax/3DRipperDX.htm
From my understanding this would cover step 1 of your project to grab
all the game textures in the current game then step 2 is to inject the
textures back into the game without altering the content.
I will see what else I can find as well as test some apps.