edit content of div?

I am working on a CMS to help speed up development of my sites but I would like to offer my clients an inline editor for there sites so they can see how the page will look before they save it.

Here is the problem the editor only edits content inside a text field but to make it a true inline editor I need it to be able to edit the content of a div. I can separate the toolbar from the target field and get it to edit multiple text fields by adding this to the custom.js file

// Place the toolbar inside the element with an ID of "myToolbar" and the elements path
// in the element with an ID of "myElementsPath".
config.sharedSpaces =
{
top : 'myToolbar',
bottom : 'myElementsPath'
};

I can get the bottom to change depending on the focus of the selected field so it sends the correct id of the field that needs editing but I cannot figure out how to make it edit the content of a div, any ideas or pointers?