installationProgress.updateInstructions Property

var u = $au.uploader({
    //...other params...
});
var ip = $au.installationProgress(u);
ip.updateInstructions("You need to update Image Uploader control. Click <strong>Install</strong> " +
"or <strong>Run</strong> button when you see the control installation dialog. " +
"If you don't see installation dialog, please try to reload the page.");
//...other params...
u.writeHtml();