I believe the way to the rear element is from the rear (the inside) of the lens mount after you've detached it from the body, just as you do to access the POD. You'll need a solid, well-fitting lens spanner to unscrew the rear lens ring without risking a scratch to the lens. Maybe cover the lens with masking tape before attempting the removal.
I've never been successful at removing fungus from lenses; they've always been etched. Florida fungus must be stronger than other strains.
Instructions for removal are at http://herron.50megs.com/fungus.htm
and other places on the web. Good luck.