I use Unlocker and UltraEdit.  Each of them attaches itself to the context menu for all items in Explorer.  UltraEdit uses HKEY_CLASSES_ROOT*\Shell\Ultraedit\Command to do so.  Unlocker dynamically adds its entry from its DLL file.

My fingers are used to right-click followed by U to start UltraEdit.  Unlocker adds itself with U as a hot-key in the menu.  Here’s how to change it.

1. Using UltraEdit, open C:\Program Files\Unlocker\UnlockerCOM.dll
2. Search for "&unlock".
3. I replaced the & with _
4. When I tried to save the file, it was write-locked.
5. I killed Explorer.exe and Unlocker*.exe via Task Manager.
6. Then I saved the file.
7. Then I re-started Explorer.