If you do a seach for "DEBUG" in the pdf Datasheet for the 18F4620, you will see that the word is used as a reseverd word. It points to the configuration bit for the In-Cuircut Dubugger (Hardware). Not the same a PBP DEBUG, which is a simple serial command (PBP Software). Your solution should work neatly. Unless, of course, you decide in the future to use the ICD feature of the chip.

Steve