At the beginning of the game Lara's shirt is only tight and see-through. At the last part of the game it will be torn so it uncovers one breast. I couldn't find one texture due to texmod/game crash. So the uncovered breast is not finished, but I think it's okay though.
You will need to force DX9 in order to run the nudemod with texmod.
Press WIN+R. Type in regedit. Go to HKEY_CURRENT_USER\Software\Crystal Dynamics\Tomb Raider\Graphics
Double click the RenderAPI file and change its value to 9. Click OK.
1. Copy Texmod in the installation folder of Tomb Raider. For me it is Steam\steamapps\common\Tomb Raider
2. In this folder you have to rename "TombRaider.exe" to "!TombRaider.exe" and "Texmod" to "TombRaider.exe".
3. Now run the game as usual. Texmod will popup.
2. "Target Application" is the renamed game exe "!TombRaider.exe".
3. In "Package Mode" choose the desired tpf. In this case it's TR2013_TightSeeThroughAndTorn.tpf
4. Press run, have fun!
If you need more information, use a search engine to find a video tutorial about how to use Texmod in combination with Steam.