BashfulBob:
Go to My Messages under MyLSF, use the Select User option to find one of your old friends, then scroll down to a 'red' message (i.e. one sent to you) and click on their user name. This is a link which should allow you send them a message which can be used to exchange email addresses etc. Provided you have not deleted their messages, this should work. If you have deleted them you may need to try the Wayback machine or something. I hope this helps.
If they don't appear under My Messages, you can find them using Info/Member List and click on the first column to send a pop-up message.