I had the same problem today, battery flat, and driver side keylock not unlocking. I could open the trunk though but was not able to open de rear doors through the ski hole.
Almost got so frustrated to smash in the window to open the door when I found a suggestion on another forum (http://forum.ih8mud.com/100-series-cruisers/603933-dead-battery-locked-out-help.html).
Luckely I have a tow bar with a 13 pin power plug (jaeger type). On this plug, pin 9 has a direct connection to the battery (grounding at pin 13).
Through this plug I was able to charge the battery somewhat and use the remote to unlock the doors (if you have a scm alarm system make sure you have earplugs as it may trigger the alarm system)
