It's possible to change at least the "A" key. I did it, but I can't figure out how to change it back to "Lock".
I wish I wrote down the steps. I think I highlighted the entry and used the delete key. You can probably search as I'm sure someone else has a solution.
Edit: Did a google seach and came up with this thread:
http://www.blackberryforums.com/gene...ck-system.html
Regards-Michael G.