You can just edit the template.
ACP --> BB Code Layout --> bbcode_code
Change to
PHP Code:
<if condition="is_member_of($bbuserinfo[usergroupid], 6,15) AND in_array($foruminfo[forumid], 5,7,8)">
<div style="margin:20px; margin-top:5px">
<div class="smallfont" style="margin-bottom:2px">$vbphrase[code]:</div>
<pre class="alt2" style="margin:0px; padding:$stylevar[cellpadding]px; border:1px inset; width:$stylevar[codeblockwidth]; height:{$blockheight}px; overflow:auto"><div dir="ltr" style="text-align:left;">$code</div></pre>
</div>
<else />
<div style="margin:20px; margin-top:5px">
<div class="smallfont" style="margin-bottom:2px">$vbphrase[code]:</div>
<pre class="alt2" style="margin:0px; padding:$stylevar[cellpadding]px; border:1px inset; width:$stylevar[codeblockwidth]; height:{$blockheight}px; overflow:auto"><div dir="ltr" style="text-align:left;">Only licensed users can view PHP code!</div></pre>
</div>
</if>
This is untested