Working with OUI variables

[gsam]

I know this is a strange way of doing things, but without going into why I want to do this....
In Miva V4 with OUI, how can I set the value of AttributeValue[1] equal to the selected car1 value?

<select name="car1">
<option value=" ">Select One</option>
<option value="volvo">Volvo</option>
<option value="saab">Saab</option>
<option value="mercedes">Mercedes</option>
<option value="audi">Audi</option>
</select>


<input type="hidden" value="Group" name="AttributeCode[1]">
<input type="hidden" value=" " name="AttributeValue[1]">