I started from a fresh switch so... might not be 100% accurate because its off the top of my head
1) Format SD Card to FAT32 using guiformat (400gb)
2) Add the Hekate Payload to SD Card
3) Enter RCM, inject Hekate
4) Backup boot0/1 and raw NAND to SD Card, grab BISkeys
5) Turn off Switch, Eject SD card, reinsert to PC
6) Move all backup files to Computer, remove all content on SD card
7) Add sx os payload to SD Card base, create Emutendo folder on SD card
8) Add "sxos" folder to root of SD card, create subfolders "xci", "nsp", "updates", "dlc" (this is optional)
9) Reinsert SD Card to Switch, enter RCM, inject SX OS.
10) Hit Run custom firmware, first time boot will generate a file, if already done you can ignore the next step.
11) Reinsert SD Card to PC, grab the license file from the SD card, upload it to the SX OS website to generate the license, place new one onto SD Card root.
12) Reinsert SD card to switch, RCM, SX OS, options, Create Emunand. It will backup your NAND for the emunand.
13) Turn off Switch once it is successful. Put your update files for choidujour onto the SD card root. Also put the choidujour .nro file onto the SD card in your sxos folder.
14) Reinsert SD Card, RCM, SX OS, there should be run custom firmware option (left-most side). On top of it, emunand enabled should be lit up.
15) Initialize the switch, go into album, look for choidujour and run it
16) Select your update folder, choose to update with exFAT if you want (I'd suggest it), then hit the go button on the bottom right (don't remember what the actual button says)
17) Disable autoRCM if you want to, when its done updating the switch will turn off (it will actually reboot so you may have to turn it off twice)
18) Add all your NSP's and XCI's to their folders.
19) Install your NSP's, updates and DLC through album and enjoy