This is a cool idea, with implementation adapted from
here.
K-Meleon 1.1 has both the original Error Console and Console
2.
To access the original, type chrome://global/content/console.xul into the address bar.
To access Console
2, type chrome://console2/content/console2.xul into the address bar.
Save either one or both in your bookmarks, or for faster access add them to your personal toolbar folder.
Versions of K-Meleon that support the sidebar don't have the error consoles, or at least not in the same place, so I couldn't test the actual linked technique. This just means more of a reason to wait for official sidebar support!