It could be done with in HTML with a table, but I doubt mobipocket/kindlegen support it. Try something like:
Code:
<table width="75%">
<tr>
<td align="center" width="33%">*</td>
<td align="center" width="33%">*</td>
<td align="center" width="33%">*</td>
</tr>
</table>