Thanks to K.Rool's hacking text and the port text (Foxdie) and ARHQ.

How to convert GameShark Codes to Action Replay and vice versa

GS-AR

Simple to use, get the GS code you want to convert, and find out what region it is in (regions listed below) then simply subtract the given number.

AR-GS

To convert back again, just get the AR code, find the region and ADD the number shown below.

GoldenEye 007 (801A0000-801E0000 region)
-18C70 in Hexdecimal

GoldenEye 007 (Very Low in RAM)
-ABO or -AB1 in Hexdecimal

GoldenEye 007 (80021000-80036000 region)
-4AB1 in Hexdecimal

GoldenEye 007 (before 80021000)
-2148 in Hexdecimal