[ic] setting shipping when recalculating checkout

[interchange-users@interchange.redhat.com (Honest to Goodness)]

On the checkout page my customer can radio button select from several
shipping options. On this event I need to 
a) cause a recalculate (not difficult) and 
b) extract the chosen shipping value and set the shipping variable to it
(looks hard).

I've looked all over for the process.html page which is a red herring so
perhaps is it compiled right into the cgi executable? Or does the same
checkout page reload itself? Then how does it extract the variable
values like the number of products and the remove checkboxes? Just
asking ...