I was searching for an answer to this myself, and I stumbled upon this thread which almost gave me the answer, then I tripped over a couple of lines of code and "Boom!" it works and I've created my own [copied from someone else] set of rules.
This is what you do...
1. First, check out this thread
www.bestofjoomla.com/component/option,co...mit,10/limitstart,0/
If you go to this page
www.bestofjoomla.com/component/option,co...it,10/limitstart,20/ at the bottom you will find a set of sample "Rules", all coded up and ready to go. Download the file and edit it to suit.
2. Go to administrator/components/com_fireboard/language/english.php and make a backup again
3. Around line 755, look for
// rules.php
DEFINE('_COM_FORUM_RULES', 'Rules'
;
DEFINE('_COM_FORUM_RULES_DESC', '<ul><li>Edit this file to insert your rules joomlaroot/administrator/components/com_fireboard/language/english.php</li><li>Rule 2</li><li>Rule 3</li><li>Rule 4</li><li>...</li></ul>'
;
4. The file you downloaded and edited contains these lines and the full rules, so copy and paste over, then save.
5. At this point you might expect to see your new rules when you go to your forum, but all you get is the Joomla! blurb.
To fix that, do the following...
1. Go to com_fireboard/sources/fb_rules.php and save it as fb_rules.php.bak just in case
2. Look in fb_rules.php, around line 39/40 and make the following
edits
<?php
/* Kill the select query that pulls out the Joomla! blurb
$database->setQuery("SELECT introtext FROM #__content WHERE id=".$fbConfig['rules_cid'].""

;
$j_introtext = $database->loadResult();
*/?>
<?php
/* Don't echo the result
echo $j_introtext;
*/?>
2. Immediately below that uncomment the line
<?php // echo _COM_FORUM_RULES_DESC; ?>
to make it
<?php echo _COM_FORUM_RULES_DESC; ?>
3. Save your amended fb_rules.php
Go back to your forum, click rules and you should have it sorted.