Selection Option Groups

Hello,

Is it possible to use selection option groups at all?

I have currently the select set up and this outputs the HTML like:

<option value="1"> … </option>
<option value="2"> … </option>

Is it possible to make it output like this:

<optgroup label="Laser">
    <option value="1"> … </option>
    <option value="2"> … </option>
</optgroup>

http://wordpress.org/plugins/si-contact-form/