Edit - Preferences -Startup Scripts
At the bottom click the "Reveal Button" this will open the folder where the script should be placed.
This script creates a panel with four checkboxs and three buttons.
The checkboxs are there so you can select the data you wish to copy from and paste to. (can be multiple documents)
Fields available are :-
Keywords, Description, Title and Headline.
Select the document you want to copy the data from, select the fields you require and press the "Select Data" button.
Now select the documents you what to paste the data to and press the "Use Metadata" button.
The "reset" button just clears all the variables and de-selects the checkboxs.