He shares a tutorial with plenty of illustrations, so it should be easier for you to perform this mod, in case you’re stuck with a newer console that doesn’t have the RAM chip footprints left onboard. The overwhelming majority of the RAM lines are shared between chips, which is what makes this mod possible – all you need to connect to the extra chips is magnet wire for extra RAM chip select lines, which are, thankfully, still available on the board.
He’s stacking new RAM chips on top of the old ones and soldering them on in parallel. brings a mod that makes RAM upgrades on v1.6 possible using an old trick from the early days of home computers. However, in the hardware revision 1.6, these footprints were removed, and RAM upgrades on v1.6 were always considered impossible. The XBox PCB always had footprints for extra RAM chips, so RAM upgrades were simple – just get some new RAM ICs and solder them onto the board. While it wouldn’t give you any benefit in most games written to expect 64MB, it does help with emulators, game development, and running alternative OSes like Linux.
RAM upgrades for the original XBox have been a popular mod - you could relatively easily bump your RAM from 64MB to 128MB.