There is always Kool-Aid to try... that stuff is wicked. I dyed my hair red for spirit day in September when in high school and had pink hair through January x( not a great idea, but it worked!
You are welcome. Prepare for a doll addictions. Food coloring should work. We have had dolls that ended up purple whe the girls were small. I do believe a marker was responsible. Sydney says there are elves but they are not barbie faced but have very large eyes and the elfin ears. She said they are anime or manga or some such thing. I could not follow since the jargon was unfamiliar to me. I think elves should be purple myself. She used the web to find out the ins and outs of painting her doll. She used acryllics and has athe tiniest brushes imaginable and also glossy and matte varnish to seal the face. We went to our local craft store for them. Good luck. I am susre your little girl will love her customized elf Barbie!
Bobbi http://www.clicksmilies.com/s0105/cool/cool-smiley-028.gif