[Opserty]

I don't know if custom fields are fetched with posts but you can try editing the postbit template:

(First make a custom userfield and all that stuff make a note of the Field Id)
Look for:

<div id="postmenu_$post[postid]">
	<if condition="$show['profile']">
	<a class="bigusername" href="member.php?$session[sessionurl]u=$post[userid]">$post[musername]</a>
	<script type="text/javascript"> vbmenu_register("postmenu_$post[postid]", true); </script>
	<else />
	$post[musername]
	</if>
</div>

Change it to:

<div id="postmenu_$post[postid]">
	<if condition="$show['profile']">
		<a class="bigusername" href="member.php?$session[sessionurl]u=$post[userid]">$post[fieldX]</a>
		<script type="text/javascript"> vbmenu_register("postmenu_$post[postid]", true); </script>
	<else />
		$post[fieldX]
	</if>
</div>

Make sure you replace the X with the ID number of the field.