You don't need to do anything special, if you are using Hekate, click launch and then CFW SysNAND. If you are using SX OS, hold "+" during boot and click the green emuMMC button, then choose Custom Firmware to launch.
Nothing to do with this, but make sure you have a NAND Backup if you haven't done it.
I am getting the following error messages when trying to launch CFW - sysMMC:
Failed to apply 'nosigchk'!
Failed to launch HOS!
I can launch CFW - emuMMC with no problems.