In X4, right click on the object you wish to be the destination and select Properties (or hit ALT ENTER). An Object Properties dialog will come up. Then on the fifth tab over, (Internet) you can designate the object as a bookmark in the Behavior pulldown. Assign it a name.
Now go to your Source object and open the Object Properties. Go to the Internet Tab again. This time in URL you will have a choice of selecting your bookmark or bookmarks if you created more than one.