I am not sure whether ACSM actually looks at individual programs and endorses them or not but I found a position paper by ACSM which recommends plyometric activities for children. Here is the link: http://www.acsm.org/docs/current-comments/plyometrictraining.pdf
The images I have seen of CrossFit make me not want to recommend it to anybody but that was (hopefully) a misrepresentation of that program. It is always important to make any program fit the participants and not the other way around.
Hope this helps.