To do what you would like to do, you need to edit the .dff file, what is the 3D file of this ped model.
Have on look on this: http://www.youtube.com/watch?v=wezvlqwE5II
Or just search a few other tutorials.
You will need 3DSMax, those tutorials right there are great (remove those links if I'm not allowed to post them ofc) :
HOW TO EDIT YOUR 3D MODEL: http://forum.ls-rp.com/viewtopic.php?f=223&t=149656
HOW TO GET 3DS MAX (FREE 30 DAYS VERSION): http://forum.ls-rp.com/viewtopic.php?f=223&t=183238
There are a lot of tutorials on internet
Tell me if you got a problem, it's not an easy thing.