don't appear to have a remote trunk release lever

Hi,

The owner’s manual doesn’t mention anything about a release lever or button for normal use. However there is an emergency boot release lever located on the inside of the boot lid.

To gain access to the emergency lever, you have to lower the rear seat backs and then reach through to the lever.

Here’s an image taken from the 2004 Mazda 6 owner manual (scroll to 3-12 and 3-13), which shows its’ location.

(click on image to enlarge for better viewing)

Hopefully this is of some help.