It is not possible to scroll through a horizontal-only ListView using a vertical mouse wheel. This is possible in widget-based applications, as long as the view cannot be scrolled vertically.

ListView {
    id: view
    anchors.fill: parent
    model: 50
    orientation: ListView.Horizontal
    delegate: Rectangle {
        width: height
        height: view.height
        color: index % 2 === 0 ? "#f0f" : "#0f0"
    }
}

Given the view can only be scrolled horizontally, using a vertical mouse wheel (regular mouse or vertical swipe on a touchpad) should scroll it horizontally, even when not pressing Alt.