Custom Error Messages & Error Callback for Logging

Love the more detailed error message in flexmonster 2.5!!!  Excellent for troubleshooting.  
How can I customize the message for the user so that:

• when ExceptionMessage = Execution Timeout Expired - have the message just say the server timed out, please check your filters.
• when ExceptionMessage = Something else - have the message say another message
• and also access the ExceptionMessage & StackTrace in a results/data refreshed callback so I can send it back to the server for error logging.

 
Unable to open file http://host.motorintelligence.net/api/flexmonster/get?id=a48e27aa-4d43-e811-90f2-eb9338291836&423357264.

It seems that this file doesn't exist or 'Access-Control-Allow-Origin' header is absent in the resource requested.

Read more info about this error
Details: {"Message":"An error has occurred.","ExceptionMessage":"Execution Timeout Expired. The timeout period elapsed prior to completion of the operation or the server is not responding.","ExceptionType":"System.Data.SqlClient.SqlException","StackTrace":" at FlexmonsterCompressor.Controllers.FlexmonsterController.Get() in C:\\inetpub\\wwwroot\\Search\\test\\FlexmonsterCompressor\\Controllers\\FlexmonsterController.cs:line 85\r\n at lambda_method(Closure , Object , Object[] )\r\n at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance