[cclaerhout]

The solution is :

For forums ID :

<if condition="in_array($GLOBALS[forumid], array(XX,XX,XX,XX))">THE CODE</if>

For usegroup ID :

<if condition="in_array($bbuserinfo[usergroupid], array(XX,XX,XX,XX))">THE CODE</if>

For the both :

<if condition="in_array($GLOBALS[forumid], array(XX,XX,XX,XX)) AND in_array($bbuserinfo[usergroupid], array(XX,XX,XX,XX))">THE CODE</if>

If you don't want some forumid or usergroupid access to the dice just use
!in_array instead in_array.