If you are using the 'textbox' component, you can bind the 'paste' event to the input box. Reset the inputed characters after pasting to the input box.
$.extend($.fn.textbox.defaults.inputEvents, {
paste: function(e){
var t = $(e.data.target);
setTimeout(function(){
var v = t.textbox('getText');
v = ... // modify it
t.textbox('setText', v);
},0)
}
})