Try using the rotary wheel for scrolling (you need firmware v.4.0.17). Put your Up and Down commands under RIGHT/ LEFT buttons and execute the action list by using executeActions.
See script in below:


Simple rotary function:

onRotary = function(clicks)
{
if (clicks > 0)
{System.print ("ROTARY Right");
//GUI.widget("PS_PAGE_UP").executeActions();
//GUI.widget("PS_CURSOR_UP").executeActions();

CF.widget("RIGHT", "ACTIONS", "RESOURCES").executeActions();
}
if (clicks < 0)
{System.print ("ROTARY Left");
//GUI.widget("PS_PAGE_DOWN").executeActions();
//GUI.widget("PS_CURSOR_DOWN").executeActions();

CF.widget("LEFT", "ACTIONS", "RESOURCES").executeActions();
}
};
//----------

It will execute actions (whatever you choose: rs232, ir, NOT script ) of buttons "LEFT" & "RIGHT", located in the page named "ACTIONS" in activity/device "RESOURCES", which of course you have to create.
You can also use it (see commented lines) to issue hard button presses (assuming that you hadn’t put any code under) like :Page+/-, CursorUp/Down, volume+/-, Program+/- whatever you fancy.