1. Go to "Tools" -> "Options..." -> "Environment" -> "External Tools"
2. Click "Add" -> "Add Tool".
3. Make the following settings for this tool:

   Executable	date
   Arguments	<empty>
   Output	Replace Selection
   Modifies current document	checked

4. Click OK.
5. Open a file from a git repository.
6. Click "Tools" -> "Git" -> "Local Repository" -> "Log".
   You'll see the log of the repository you opened the file from.
7. Place the cursor somewhere in the log.
8. Click "Tools" -> "External" -> "New Tool".
   The current date and time will be inserted into the log.

The git log editor should only display the git log. It should not be editable.