Use the PC serial port connector to your SP3. Turn everything on.
Load MapSource on the PC.
Press the icon to upload from the SP3 to the PC.
You'll get a window asking what you want to upload (routes, tracks, waypoints etc). Ensure that waypoints is checked. Upload.
The waypoints will now appear on the waypoint tab on the MapSource window. If you wish to save them, create and name a file.
To download them, connect your Quest and reverse the process.
Greg