Create different URL alias based on CCK field
I'm assuming you're well-versed in the settings that Pathauto gives you (like it's own "automated alias" checkbox, and the settings that change what happens when a node is updated).  I'm assuming those settings don't meet your needs.

This should be possible, but not in the theme layer.  You'll need to write a module, probably a relatively small one.  You'll need to implement hook_nodeapi in D6 or one of the hook_node* family in D7, and maybe hook_pathauto, to make sure the right thing happens.

Drupal 6


hook_pathauto()
hook_nodeapi()


Drupal 7


hook_pathauto()
hook_node_presave()