The resistance faces are named "FaceR01" thru "FaceR04". The female faces are named "Eva", "Kamila", "Lada", "Luci", "Marketa", and "Nada". You can set the face of a unit by typing this in it's init field:
this setface "facename"
However, always use the 'setidentity' command for actual missions, since the 'setface' command is reset after loading a saved game.