Scrolling a dynamic text box with mousewheel

Hi,

Can anyone tell me what is the most simple way of using the mousewheel to scroll a large text inserted in a dynamic text box of a Flash MX 2004 movie. I also use to buttons to scroll the text up and down. Here is the code for that (this code in applied to a movie that has a button inside):

onClipEvent ( enterFrame ) {
if (lMouseover) {
_root.texto.scroll += 1;
}
}

Thanks for any help

Regards

RicFerr