How to simulate clicking on javascript button

[renodays]

guys, i am trying to simulate clicking on a javascript button that moves an item from one list to another list.

<a href="javascript:moveSelectedItems(document.report.fromList, document.report.toList)"><img src="../images/b-addList.gif"></a>

function moveSelectedItems(fromList, toList) {
    moveOneWay(fromList, toList);
}

function moveOneWay(fbox, tbox) {
var arrFbox = new Array();
    var arrTbox = new Array();   
    var arrFvalues = new Array();
    var arrTvalues = new Array();
    var i;
    for (i = 0; i < tbox.options.length; i++) {
        arrTvalues[i] = tbox.options[i].value;
    arrTbox[i] = tbox.options[i].text;
    }
    var fLength = 0;
    var tLength = arrTbox.length;
    for(i = 0; i < fbox.options.length; i++) {
        if (fbox.options[i].selected && fbox.options[i].value != "") {
            arrTbox[tLength] = fbox.options[i].text;
        arrTvalues[tLength] = fbox.options[i].value;
    tLength++;
    }
    }   
    tbox.length = 0;
    var c;

    for(c = 0; c < arrTbox.length; c++) {
        var no = new Option();
    no.value = arrTvalues[c];
    no.text = arrTbox[c];
    tbox[c] = no;
}
}

[renodays]

how could i simulate clicking on that button using httpunit?

WebResponse response = wc.getCurrentPage();
WebForm wf = response.getFormWithName("Report");
WebForm.Scriptable wfs = wf.getScriptableObject();
-----not sure how to simulate the situation -----
wf.setParameter("fromList", ... ????
wf.setParameter("toList", ..... ????
wfs.submit();