Hi Gary,

Yes, you can set value of the WebProgressBar using Javascript. You can use the following line of JavaScript code to set the value:

     var progressBar = $find("WebProgressBar1");
     progressBar.set_progressValue(20);

The following link will give you more details:
<http://help.infragistics.com/NetAdvantage/ASPNET/2010.1/CLR3.5/?page=WebProgressBar_Using_WebProgressBar_as_an_AJAX_Progress_Indicator.html>

Please let me know if you need any further assistance with this matter.