Good luck.
I recall in Dave's DVD on hand and feet casting he recommends not to cast in that age range.
Hands and feet is not my speciality, but have done a few.
We did a casting of a brother and sister for a friend. The Boy was 1 year old and although he was not wild, he would hold his hand in the alginate (with some help from his mother), but kept wiggling his fingers. When we looked into the first mould we could see the fingers were a bit messed up. So we did it again and it was even worse. I cast both of them, and my wife did a very good job of fixing the fingers (she spent many hours since it was for a friend).
The sister was about 3 and her mum just told her to play freeze with her hand in the alginate and the casting was perfect.
They were a Christmas gift for the father. He was very impressed, but asked why there was less skin detail on his son's cast. When we explained what it looked like before we fixed it, he was happy.
The only suggestion I have is to try and do it when they are sleeping.
Regards
Ray Hope
B Immortal Body Casting
http://www.bimmortal.com 
