Jon wrote a great article how to add a custom command. Quoting from Jon's post: "All in all I find IPad to be a really interesting and powerful text editor - but being able to customize the menus and commands with such ease I think is just another example of the cool work the Oslo team is doing for us as developers." 

For details see:  http://www.masteringbiztalk.com/blogs/jon/PermaLink,guid,92ec6f1f-45e5-4b7d-b675-548be5131a07.aspx