You have a good start. I would recommend the following: 1) create a transparency map for this image using your art program (photoshop, etc) 2) then place the transparency & this image on a square in Poser. 3) arrange model to fit the shirt & set lights to match shirt's lighting 4) add pants to the model 5) remove the square with the shirt & save the image of the poser figure (sans shirt) for import into your art program (note: this step helps keep everything on a flat plane.) 6) using layers, place the shirt back over the imported image of the poser model. Touch up as you like, add backgrounds, text, etc. There ya go! Looks like a lot of steps, but it isn't.