There is no need for the "system transfer method" or any other method requiring a second 3DS anymore. The Guide includes methods that work on the most recent firmware.
(Technically, when you use the brute-force method of calculating your moveable.sed and you add another 3DS to your Friends list, another 3DS is getting involved to generate the "seed" for the calculation – but the process is automated and there's no benefit to generating the seed on your own.)