(http://i.imgur.com/DhXNuk6.png)
Step 1: If you want your map to have a portal in Cape, check the "Has Portal" box.
(http://i.imgur.com/A7vU527.png)
(http://i.imgur.com/SxyIbl2.png)
Steps 2 & 3: Set the destination for the portal when arriving from Cape into your map.
Note: If it is all set to 0, it will be in the top-left corner of the map!
(http://i.imgur.com/I4mEC1k.png)
Step 4: If you set a destination for it, you can jump through it to get it's information so that you can create a portal that only goes back to Cape.
(http://i.imgur.com/EOImwa3.png)
Step 5: Go to the Objects tab and in the portal field type "fhCapeOfWorlds" as this is what the map is actually called by the game.
Step 6: Type in the destination info you saw earlier, this is where you will arrive in Cape!
Steps 7 & 8: Now click new object and place the portal where you want it to be.
(http://i.imgur.com/Vmch4GI.png)
Step 9: Make sure everything is correct before moving on!
This teaches you how to:
Set your map to have a portal in Cape.
Easily find the Cape of Distant Worlds editor name and coordinate info.
Place a portal that only leads to Cape.