It seems the blog is justified because somewhere in the css (I couldn't immediately find where), class_blogcontent contains "text-align: justify". So if you could figure out the class for the CMS content you should be able to add something similar. Or it seems like you should be able to create a custom JUSTIFY bbcode by making the replacement something like:
Code:
<span style="text-align: justify;">{param}</span>
but I haven't tried either of these methods yet.