You *should* be able to just install a CN cia and run it from there. Not tested though...
I can run CN via SYSNAND ONLY if I boot up SYSNAND with rxMode. Otherwise, if I'm on default SYSNAND I can't run the CN app that I installed (gives the same message as H&S app on SYSNAND without rxMode)
I've tried installing Pasta running SYSNAND with rxMode on, but that fails and just spits me an error message and my 3DS restarts