Download a program called fmXML. (You can get it here:
fmXML) When you install it open the program and you should see a text box at the top with a button next to it labelled 'Browse.' Click that button and navigate to the folder your facepack is located then click the 'OK' button. Make sure the 'faces' checkbox is ticked then press the 'GO!' button. A small dialog box should appear with the filename in a greyed-out textbox, two smaller textboxes, one with a '0' typed in, and another greyed-out one with a number followed by a slash then another number. Basically this box tells you what file it is and out of how many, for example file 1 out of 5. In the box labelled with '0' you must enter the players unique ID which can be found in FM by going into your preferences and tick the checkbox next to 'show unique IDs.' Go to the players profile in FM and the unique ID should be displayed underneath the players name. Enter this information in the box and click the 'Add' button, repeat this process for the rest of the faces. I hope this helps. :-).