Basically, idea is to add a pattern unlock in script, running on a computer, connected to phone via adb. So, something like adb shell input events. Pattern is KNOWN, no hacking.
This is an old question but in the interest of helping anyone who finds this post, check out my android-pattern-unlock shell script.
It uses ADB's sendevent to draw a known unlock pattern into the lock screen. Worked for me and allowed me to gain access with a broken screen.