You will need a 3DS running Luma CFW, as well as a computer that is capable of creating an access point or running a proxy.
It is necessary to disable Root CA Verification in order to capture all 3DS traffic. We recommend doing this with SciresM's 3DS-SSL-Patch.
For ease of use, you can download this premade code.ips patch and place it at /luma/titles/0004013000002F02/code.ips on your 3DS' SD card. Make sure that you've enabled Luma's game patching feature by holding down the select button while powering on your 3DS.