Actually I don't know if "deny none" is needed or not. I just found it on a webpage back when I did the modification.
I don't really see any commands with "slug" in them. Whenever the text says "slug" or "NSLU2", just imagine it says diskstation instead.
The first commands shouldn't be needed, as the diskstation already has a /root directory. You do need to run the following commands (mkdir .ssh and so on) exactly as stated.
When you reach the "nano" command, you don't need to do the rest, if you have already changed /etc/ssh/sshd_config as I've described yesterday.
Now you can reboot. There is a script somewhere that can restart the sshd server without rebooting, but I can't remember exactly where that is on the Synology. It isn't as the webpage states. Just reboot, that is much easier.
In case of anything going wrong: Make sure you can access the diskstation with ordinary telnet before you begin. If you only have ssh access, and you screw up something with ssh, you're in deep cow dung. But with telnet, you can access the diskstation without ssh, and fix whatever has happened.
And to be able to fix things, make sure you keep a copy of the original /etc/ssh/sshd_config file. Just make a copy before you start editing it, like this:
"cp /etc/ssh/sshd_config /etc/ssh/sshd_config.original"
And perhaps we should start thinking of moving to the appropriate "modding" section