[kh99]

You can edit the postbit (or postbit_legacy, if your user info is on the left) and you'll find some code like this (the code below is from postbit_legacy, but it's similar in postbit):

<if condition="$show['avatar']">
	<div class="smallfont">
		&nbsp;<br /><a href="member.php?$session[sessionurl]u=$post[userid]"><img src="$post[avatarurl]" $post[avwidth] $post[avheight] alt="<phrase 1="$post[username]">$vbphrase[xs_avatar]</phrase>" border="0" /></a>
	</div>
</if>

the part in red tells where the avatar links to, so you could change it for one user by doing something like:

<if condition="$show['avatar']">
	<div class="smallfont">
		&nbsp;<br /><a href="<if condition="$post[userid] == X">URL<else />member.php?$session[sessionurl]u=$post[userid]</if>"><img src="$post[avatarurl]" $post[avwidth] $post[avheight] alt="<phrase 1="$post[username]">$vbphrase[xs_avatar]</phrase>" border="0" /></a>
	</div>
</if>

of course you want to change the parts in blue to your userid and the url you want to go to.