Turn location CCK 'city' field into taxonomy autocomplete field I am using the "Taxonomize Location" module to automatically save all Location CCK Field submissions into the "location" taxonomy. Terms in the location taxonomy are saved in 3 layers: Country -> Province -> City.

The location CCK field offers Country and Province as select lists, and City merely as a text field. Is it possible to display the City field as an autocomplete field that pulls city suggestions from the third layer of my location taxonomy, depending on what Country and Province was selected?
What you can do is use hook_form_alter.
You will define an #autocomplete_path and use hook_menu to create a menu item for this path. In hook_menu, you will define a page callback. This will be a function that will return the list of cities from your taxonomy items.