How to make a hide button for an existing plugin

[Starnova]

I am using this plugin:
http://mods.mybb.com/view/hide-to-guests

which uses [hide][/hide] and would like to make the posting easier for me since I do most if not all of it on the forum.
How would I do this? I was hoping to build the button function like the other buttons on the postbit,Image, insert hyperlink. where I would highlight the text and then press the button for the code to appear.