Ajeh, maybe you have a better idea, but after looking for several hours I've not found a good way.

Unfortunately, it doesn't look super easy. I was thinking I could exploit the way Zen Cart handles links to products that have been loaded into the shopping cart. Zen Cart uses an MD5 hash to preselect the attributes on the product page after clicking on a configured product that has been added to the shopping cart. I haven't spent much time fiddling with this idea, however.