It's possible. All you need is the player's .fsh and .ebo files, which you can extract from plyrface.viv (faces, the .fsh files) and plyrlodb.viv (headshapes, the .ebo files).
- Place the .fsh and .ebo files in the sgsm folder.
- Rename the .fsh file; it cannot be the same as the regular PLAYERPKG value they use. For example, if you wanted to use Shaq's face, you could rename the .fsh file shonea_.fsh; anything you like, so long as it wasn't the regular shoneal.fsh.
- Rename the .ebo file using the same seven character value you used before (eg shonea_). The headshape (.ebo) for coaches is also named a little differently, the PLAYERPKG value is followed by A_head in the filename. Again using Shaquille O'Neal as an example, you would need to call the file shonea_A_head.ebo.
- When you're editing coaches.dbf, remember to use the appropriate PLAYERPKG value that corresponds to the newly renamed files (eg SHONEA_). Fill in the rest of the data as necessary.