Now I have discovered how to do that, I made a video, because it's a fun little thing to do and trying to work it out on your own by bugging more expereinced modders is not fun.
The video assumes a bit of knowledge, but I thought I would share it for those of you keen to make tiny white mammoths, without making all mammoths tiny and white.
http://www.youtube.com/watch?v=9MYG4IvgKGo&hd=1
ENJOY!

I openly encourage others to post solutions to problems they have had, to make it easier for the next person to encounter it 