YOu should try using Oedit to view what your textures look like - it lets you open the .o file (the head model) that accompanies the .fsh files in the each of the respective .big files. It lets you view the texture you've made on the head model (and you can spin, zoom, pan etc.) before you save anything, and before you enter the game! it makes it a lot easier than modding the texture, converting it back to fsh, opening the game, trying to find which team your new texture is, then waiting for the camera to zoom in on it, only to discover your texture looks like poo!
As you would've seen, player faces suit particular models and don't always seem to fit on some, so oedit lets you find a model that is of correct size...or you can simply muck around with the model itself (cheekbones, eyes etc.)
You can alter the model itself, however I know in some games it can have ill - effects. However I know of people who have used this or programs that are similar to this and have completely remodel things in the game without any problems (i've seen some major car modifications made in NFSU for example) however it requires a bit of know how and patience. So in theory, you could give Andrew Flintoff a nice big member on his forehead, like he deserves