First, the reason behind these is to make things simpler for the user, nothing else. They do require some basic knowledge of the DC protocol, which I will not describe here.
Right, then let's get to the meat of the matter. To specify user commands, go to the "Extended" settings page. There, you can see three fields, "Title", "Command" and "Seperator".
The "Title" field contains the title(s) of the commands (e.g. the name of the menu items).
The "Command" field contains the commands(s) (e.g. what is actually sent to the hub).
The "Seperator" field contains the string that is used to seperate the commands and titles.
That said, here's an example of a homebrewn ban command, coupled with a show IP command and a slotbegger command as well as a kick command (just for fun):

Title	Ban user#Show IP#Beg for a slot#Kick user
Command	<%n> ban %u|#$ShowIP#$To: %u From: %n $<%n> Can I have a slot plz?|#$To: %u From: %n $<%n> You are being kicked|<%n> %n is kicking %u|$Kick %u|
Seperator	#

The different "insert" commands are listed below (the list may be incomplete) :

Command	Effect
%email	The contents of the email field of the user(s) selected (one at a time)
%ip	The IP of the user(s) selected (one at a time)
%lock	The lock of the user(s) selected (one at a time)
%n	Your current nick in the hub
%u	The user name of the user(s) selected (one at a time)

As you saw in the example, there exist a special command ($ShowIP) which shows the users IP locally. For the client to know the IP of a user, it has to have contacted the user before, otherwise the IP will be "UNKNOWN".

If you have any suggestion that you think ought to be here, mail me (don't forget to remove the three exclamation marks).