simply export the arm texture of sendoh using mod tool. should be the 1st or 2nd subfile. then download the tattoo you want to use. open the arm texture and the tattoo pic with photoshop. copy the tattoo texture into a new layer over the arm texture. resize it so it fits within the arm section you wish to apply it. then select the tattoo layer and go to the blending options drop down menu and select multiply. this will make your tattoo texture more realistic. then turn down the opacity from 100% to 70%. once your done with all that, save the whole file as a DDS with a DXT5 setting. import it back to the arm file in mod tool and you should be good.