Adding keyboard navigation to a CheckBoxList in dropdown

Question

I have a "DropDownCheckBoxList" user control I created from scratch using a Textbox, an Image (the arrow) and a hidden ASP.Net CheckBoxList control in a drop-down DIV.

Combined with a lot of JQuery it works well except for one last feature... keyboard up/down navigation of the drop down list items.

It looks like this:

A sample of the generated HTML is shown below:

<div style="width: 170px;" class="dropDownComboxBoxList">
    <div onclick="DropDown('#MainContent_DropDownCheckBoxList1_dropDownDiv', '#MainContent_DropDownCheckBoxList1_dropDownTextBox')" class="dropDownControl" id="MainContent_DropDownCheckBoxList1_dropDownControl">
        <div style="width: 150px;" class="dropDownLeft">
            <input type="text" class="dropDownEdit" id="MainContent_DropDownCheckBoxList1_dropDownTextBox" readonly="readonly" value="Item 0, Item 1" name="ctl00$MainContent$DropDownCheckBoxList1$dropDownTextBox">
        </div>
        <div class="dropDownRight">
            <img src="http://localhost:28071/Images/DropDown_off.gif" class="dropDownImg img-swap" id="MainContent_DropDownCheckBoxList1_dropDownImage">
        </div>
    </div>
    <div style="width: 300px; max-height: 300px; margin-top: 0px; display: none;" class="dropDownDiv" id="MainContent_DropDownCheckBoxList1_dropDownDiv">
        <table style="height: 40px; width: 290px;" class="checkBoxList dropDownTable" id="MainContent_DropDownCheckBoxList1_checkBoxList">
            <tbody>
                <tr class="checkSel">
                    <td><input type="checkbox" value="0" checked="checked" id="MainContent_DropDownCheckBoxList1_checkBoxList_0" class="dropDownCheck"><label for="MainContent_DropDownCheckBoxList1_checkBoxList_0" class="dropDownLabel">Item 0</label></td>
                </tr>
                <tr class="checkSel">
                    <td><input type="checkbox" value="1" checked="checked" id="MainContent_DropDownCheckBoxList1_checkBoxList_1" class="dropDownCheck"><label for="MainContent_DropDownCheckBoxList1_checkBoxList_1" class="dropDownLabel">Item 1</label></td>
                </tr>
                <tr>
                    <td><input type="checkbox" value="2" id="MainContent_DropDownCheckBoxList1_checkBoxList_2" class="dropDownCheck"><label for="MainContent_DropDownCheckBoxList1_checkBoxList_2" class="dropDownLabel">Item 2</label></td>
                </tr>
                <tr>
                    <td><input type="checkbox" value="3" id="MainContent_DropDownCheckBoxList1_checkBoxList_3" class="dropDownCheck"><label for="MainContent_DropDownCheckBoxList1_checkBoxList_3" class="dropDownLabel">Item 3</label></td>
                </tr>
            </tbody>
        </table>
    </div>
</div>

I have tried hooking up to jQuery.keynav and then to jQuery.navigate but although both do capture the key presses, they do not have any effect on selection and the key-up/down still just scrolls the dropdownlist (when there are more items of course, unlike this sample).

The current hookup for jQuery.navigate would be like this for the HTML shown:

$('#MainContent_DropDownCheckBoxList1_checkBoxList').filter('td').navigate({ mouse: true, activeClass: 'checkHover' });

Any ideas what more I need to do to get it to navigate? Is it just an issue with using the CheckBoxList in the drop down? Am I misusing the navigation add-ins?