http://en.njol.ch/projects/skript/doc/commands

Code (Text):

1. command /commandname <arguments>: # arguments are explained below
2.     description: A description of what this command does
3.     usage: How to use the command, e.g. /commandname <arguments>  # If omitted this defaults to something similar to how the command was defined above.
4.     permission: required.permission.to.use.this.command  # If omitted this command can be used by everyone regardless of permissions.
5.     permission message: Message to send if the player doesn't have the required permission to use this command  # If omitted this defaults to "You don't have the required permission to use this command"
6.     executable by: players/console/players and console  # If omitted this command can be executed by players and the console.
7.     aliases: /c, /comname. # a list of aliases of the command which are usually abbreviations of the command
8.     trigger:
9.         put conditions and effects here that will be checked/executed when the command is used.

 

So.. this doesn't work?

Code (Text):

1. on command "/skript help":
2.     wait 3 ticks
3.     send "&aInteresting... Is this the skript's help command?"

Pay attention it will only detect "/skript help" - not "/sk help"

 

Yes, those commands probably can't be canceled, because you could cancel /sk reload command and then you'll be no longer able to reload plugins.