OK, a slight advance on this.  It appears that one of the ready made
scripts in /Applications/AppleScript/Example Scripts/Info Scripts is
called Current Date & Time.scpt.

So you run ScriptRunner and have that little rocket floating around on top
of your desktop.  To get Date and Time into your TextEditor document you
the only have to:

1: Mouseclick on the rocket

2: Choose Info Scripts/Current Date and Time from the resulting pulldown
menu.

3: This produces a dialogue that displays the current date and time, and a
lozenge called Clipboard.  Click on the Clipboard lozenge.

4: Dismiss the dialogue that says "The date is on the Clipboard"

5: Use Cmd-v to insert it into the text.

So assuming ScriptRunner is already running, in a mere three mouseclicks
and one key combo you can add the current date and time into any text.  In
my book this is still three mouseclicks over the odds.  Anyone know how to
reduce this to one single key combo?

--
el bid