Hmmmm not sure if this will work, but I use it to place forum specific text content below the header. You might be able to modify it to fit your needs. Just change the array number to coincide with your forum id.
Code:
<if condition="in_array($GLOBALS[forumid], array(4))">
<tr><a href="mylink.php">text here</a></tr>
</if>
<if condition="in_array($GLOBALS[forumid], array(105))">
<tr><a href="mylink.php">text here</a></tr>
</if>