How do I change the field title on the "Generate automatic URL alias" checkbox in pathautho? How do I change the title of the checkbox "Generate automatic URL alias" on the pathauto fieldset on the node add page?

In my hook_form_node_form_alter I don't see this anywhere in the $form.
One option is to utilize the String Overrides module. Depending on exactly what you are trying to do, it may be a bit easier to administer and manage this change via the admin rather than in code.