Edit skin/reboot/modules/Product_Options/customer_options.tpl
Replace...
Code:
<div class="span5 property-name product-input">
With...
Code:
<div class="span3 property-name product-input">
Then replace...
Code:
<div class="span7 property-value">
With...
Code:
<div class="span9 property-value">
Columns are totally flexible, based on Bootstrap's grid system
