The "How to do it" appears to be almost stupid-easy !!
This is copied from the phpbb site:
"To use any of the following custom BBCodes, navigate to the Posting => BBCodes section of the phpBB3 administration panel and click the "Add a new BBCode" button. Enter the respective code from below into the "BBCode usage" and "HTML replacement" boxes."
Code: Select all
<span style="text-decoration: line-through;">{TEXT}</span>
THANK YOU VERY MUCH FOR CONSIDERING THIS REQUEST !!