There is another way w/o having the edit freq issue if you can point to 125°W and scan in the EWTN's there then go back to 91°W and modify the A/P IDs and name, then delete the rest of the channels on that mux.
EWTN is on 3720 on 125W.
On my 6K with one of the "aftermarket" FW versions (OEM does not have tone on scan) I can do as Tony says but it doesnt ask to save just does "Saving ...Please wait when you exit out of the manual scan screen.
Try the 125W trick if you can hit that bird.