Chi, you are going to need to do this in php to assign the variable to smarty, then you can access it in your tpl.
Look at news_manage.php, and see how the variable is being assigned to smarty, and the queries that are being used. Then do a recursive search of your X-cart to see where the current news_message variable is being assigned, and then insert your example logic there.
After that is complete you will have passed the variable to smarty, and you can then work with it in templates like you would any other. You are probably going to need a {section} or {foreach} loop to go through your newly assigned array and display each message in the template.
Definitely not for the faint of heart.
I can do this for you if you like, that's what I do.
-Mike