Ok, try this. Replace this:
Code:
<INPUT id="po{$v.classid}" type="text" name="{$poname}" value="{$v.default|escape}">
with this:
Code:
{if $v.classtext eq 'option text here'}
<textarea id="po{$v.classid}" type="text" name="{$poname}" value="{$v.default|escape}" cols="60" rows="10"></textarea>
{else}
<INPUT id="po{$v.classid}" type="text" name="{$poname}" value="{$v.default|escape}">{/if}
replace 'option text here' with the actual Option text of the option you want to display the text field for. Let me know if it works for you.