Programs Needed
Entity (latest version)
Step One:
Open the map with your added/new teleporters. Find the scnr tag and click it.

Step Two:
Right Click the the middle window and Select Clone Chunk.

Step Three:
In the Chunk Cloner find Scenery Placement

There should be a bunch of Chunks, scroll to the bottom chunk and remember the number of the last chunk, in my case 25. Now clone a chunk for every teleporter you added. If you added four teleporters, clone 4 chunks.
Step Four:
Now click Meta Editor and scroll down to Objective Locations.

Find the XYZ coordinates of your teleporters and write the numbers down.
Step Five:
Still in the Meta Editor scroll up to the Scenery Placement.

Now, since my final Scenery chunk number was 25, my clone chunks will be 26, 27, 28, and 29. Select the first cloned chunk, 26, and make the XYZ coordinates the same as the teleporter.
Step Six:
Below the Scenery Placement in the Scenery Palette. Find the Palette number, mine was three, where the scen is objects\multi\2way_teleporter_variant\2way_teleporter_variant
or
objects\multi\2way_teleporter\2way_teleporter

e.g. Gemini is 3, where as Warlock is 1
The teleporter_variant is blue while the other is green.
Go back up to Scenery Placement and find your cloned scenery and make sure the top value

is the same as the Palette chunk number of the appropriate Scenery, in my case 3.
Now repeat Step Five and Six for every teleporter.
Now sign your map, FTP, and play with your fully visible teleporter.
If you need any help, or you see something I missed, please PM me.