I'm not familiar with the 740S, so I down loaded the manual and I can appreciate your situation. It looks like you can possibly use the procedure outlined on page 30. Take a look at the procedure for moving a saved waypoint. The last step in this procedure indicates there is an option to select and move a waypoint by entering coordinates. You may have to create an arbitrary waypoint, select it, and then edit to move it where you want it. Bluewaterpirate I'm sure knows the best way. I hope this post gets it bumped up for you and Tom will let you in on the secret.