For VB4 look for the following code in postbit_legacy:
Code:
<div class="username_container">
<vb:if condition="$post['userid']">
{vb:raw memberaction_dropdown}
{vb:raw post.onlinestatus}
<vb:else />
<span class="username guest">{vb:raw post.musername}</span>
</vb:if>
</div>
<span class="usertitle">
{vb:raw post.usertitle}
</span>
And put the following below it:
Code:
<vb:if condition="$post[usergroupid] == XX"><img src="images/misc/xxxxxxx.gif"></vb:if>
Otherwise follow the original instructions...
In general IF statements remain the same between VB3 and VB4 except add "vb:" in front of the "if".