(function(){
//Section 1 : Code to execute when the toolbar button is pressed
var a= {
exec:function(editor){
editor.insertHtml('[[MORE]]');
}
},

//Section 2 : Create the button and add the functionality to it
b='readmorebtn';
CKEDITOR.plugins.add(b,{
init:function(editor){
editor.addCommand(b,a);
editor.ui.addButton("readmorebtn",{
    label:'Insert "Read more" link', 
    icon:this.path+"readmore.png",
    command:b
    });
}
}); 
})();