Managed to find out how:
function callback_wrap(e, c, ed) {
var course = getSelectedText("_lesson_course");
var module_info = jQuery("#title").val();
var module_nr = module_info.match( /\d+/g );
var start = ed.canvas.selectionStart;
var end = ed.canvas.selectionEnd;
var content = jQuery("#content").val();
console.log(start);
console.log(end);
console.log(ed);
var selected = content.slice(start, end);
var string = '<div class="moudle-area">'+selected+'<p>[Tweet "I just completed Module '+module_nr+' of the '+course+' Course"]</p></div>';
QTags.insertContent(string);
}
QTags.addButton( 'eg_wrap', 'WRAP ARROWND', callback_wrap);