Hi Satish,

I have followed the below steps and was able to customize the busy indicator:

1. Create a binary file with custom image (say "newbusyindicator")
   
   
2. Save-as the UserWorkForm in the available Application ruleset, add the below snippet in HTML Source.

                <script>
                      pega.ui.busyIndicator.prototype.createIndicatorImage = function() {
                      if(this.oSpan == null)
                      this.initialize(this._sNode);
                      var oSpan = this.oSpan;
                      if (this._message && this._message.length > 0) oSpan.innerHTML = "<img src = 'webwb/newbusyindicator.gif'   alt='loading' />" + " " + this._message ;
                      else oSpan.innerHTML = "<img src = 'webwb/newbusyindicator.gif' alt='loading' />";
                    }
                </script>