Not that anyone asks me but ; )
...after fighting with CMPS, I opted to prefix profile.php with $vboptions[bburl]/ and it works well (for me and vbAdvanced)
Code:
<if condition="$vbulletin->options['invitation_usercp_link']">
<tr>
<td class="$navclass[invitation]" nowrap="nowrap">
<a class="smallfont" href="$vboptions[bburl]/profile.php?$session[sessionurl]do=invitation">$vbphrase[invitation]</a>
</td>
</tr>
</if>