Wijchartnavigator allows you to set the minimum and maximum values of the navigator. You can use the rangeMin property to set the start (left) range of the navigator and rangeMax property to set the end (right) range of the navigator.

$("#wijchartnavigator").wijchartnavigator({
    targetSelector: "#chart1",
    rangeMin: $.toOADate(new Date("2014/2/5")),
    rangeMax: $.toOADate(new Date("2014/2/28")),