How to authorize device for adb when the touch control is completely broken?

My Nexus 7 2012 has fallen from a table and though the display as well as the device itself is fine, the touch control is completely broken. You cannot tap or touch anything. I believe I can manage a restricted access to it (thanks to great tutorial: http://www.reddit.com/r/Android/comments/1r2zha/how_i_managed_to_use_my_android_device_with_a) if only I can execute adb commands. Unfortunately any attempts end with simple: $ adb shell error: device unauthorized. Please check the confirmation dialog on your device. Which is no option for me as my touch control is gone :-(. I am looking for any option how to bypass/authorize the confirmation without using the device's touchscreen.