The website Objectif Tintin lets you read Rodiers entire finished version of Herges last unfinished Tintin-adventure at:
http://objectif-tintin.nu/online/alph-art/

This is, in my regard the best version, and the only one available in English. In French you can also find the version of "Ramo Nash"
http://tintin.100foros.com/sab-sep-30-2006-213-am-vp67.html

And the somewhat more crude "Pierre" version:
http://membres.multimania.fr/zenzirabd/minimaliste1.html

There is also a version by "ENSBA Paris", but it does not seem to be available online.