i have a control panel on a website that has allows a user to do a mail merge, pulling information from a MySQL database.

currently they know to type like this in a text area, similar to this forum.
____________________________
Hello <$customername>,

our next meeting is set for <$meetinglocation> at <$meetingtime> blahblah, and so on...
___________________________

when they are done and click submit and it prints the messages for the selected customers.

here is the question, what i have seen and would like to do is have a list outside of the text box of the available fields they can pull from and when they click the field name on this list it "pastes" the correct code into the text area at the cursor location.

this may be java and not PHP but if anyone knows the best way to do this, let me know!

Thanks
Sean