At the moment, this is something I feel may cause too much complexity and inflexibility to code in as a feature to the theme. Unfortunately I don't have the time to figure out the code for you, but if you look at the code from the following links, you may get an idea of how to achieve this in your situation.
Comments
Comment #1
andregriffin commentedAt the moment, this is something I feel may cause too much complexity and inflexibility to code in as a feature to the theme. Unfortunately I don't have the time to figure out the code for you, but if you look at the code from the following links, you may get an idea of how to achieve this in your situation.
http://www.cssplay.co.uk/layouts/threecol.html
http://www.smashingmagazine.com/2007/01/12/free-css-layouts-and-templates/
http://www.intensivstation.ch/en/templates/
Comment #2
andregriffin commentedUpdated discussion about this issue is here: http://drupal.org/node/321566#comment-1100614
Comment #3
andregriffin commentedMerging into this issue: http://drupal.org/node/321566