mod req : anyone can do? ajax inline post edit ???

This type of thing doesn't require AJAX, you can do this quite simply by writing a little JavaScript function that enables the browsers RTE for a particular area.

For IE:-

document.getElementById('AreaYouWantToEdit').body.contentEditable = true;

For other browsers:-

document.getElementById('AreaYouWantToEdit').editor.designMode = 'on';

This would certainly be the simplest way and saves writing lots of extra unnecessary AJAX code.