[chitown]

edit the showthread reply box
find :
<smallfont><a href="javascript:checklength(document.vbform);">[check message length]</a></smallfont></td></tr>

after that place:
<!-- private text hack [ g-force2k2 ] -->
</tr>
<td bgcolor="{secondaltcolor}" valign="top" nowrap><normalfont><b>Private Text Options:</b></normalfont></td></tr>
<tr>
<td bgcolor="{secondaltcolor}"><smallfont><input type="checkbox" name="dopriv" value="no"><b>Add a private text message to the post?</b><br><input type="text" class="bginput" name="privuser" size="20" maxlength="50" value=""> <b>Username to send private text to?</b><br><textarea name="privmsg" rows="7" cols="100" wrap="virtual" tabindex="1"></textarea></td>
<!-- private text hack [ g-force2k2 ] -->
</tr>