<table border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td valign="top">The answer to this question is true</td>
<td valign="top"><input name="yaynay" onclick="this.parentNode.parentNode.childNodes[3].firstChild.selectedIndex=1;" type="radio" />True</td>
<td valign="top"><input name="yaynay" onclick="this.parentNode.parentNode.childNodes[3].firstChild.selectedIndex=2;" type="radio" />False</td>
<td valign="top">{:MULTICHOICE:=True#~False#}</td>
</tr>
</tbody>
</table>

On clicking one of the radio buttons the Moodle MULTICHOICE is set. If you change anything in the table structure you may need to change the DOM path from the radio button to the MULTICHOICE field (that's the onclick command string).

You can see that the radio button values are not preserved after submission but with a little bit more work they can be restored and then you can hide the MULTICHOICE filed by setting the TD display style to none.
I hope that helps. Let me know if you need more details.
Itamar