Use File>>Save Campaign Cartographer File, then click Create. On the Introduction wizard page, turn off all contours except "Altitude" and make sure "Basic" is selected; select Next to move to the Basic Contour Settings page. Turn off Draw Filled Contours and Draw Contour Outline, leaving Draw Coast Outline checked (alternatively, keep all of the defaults on this page and set the "Contour Intervals" setting to something like 50000 feet, or to where the number of contours shows as "1 Contours"); select Next. On the Detail Level page, select the options that you'd like; select Next. On the Other Items page, uncheck everything; select Finish to enter a name and finish creating the new setting file. Now export your world file and load it into CC3 (you may need to zoom extents to properly see everything).