I am trying to figure out a way to have health monitoring throw
different Event IDs into the event log, and am having a hard time.
None of the customization that I have looked through so far has been
helpful, yet.

As an example, here's a text copy of a typical unhandled exception
from the event log:

Event Type:    Warning
Event Source:    ASP.NET 2.0.50727.0
Event Category:    Web Event
Event ID:    1309
Date:        6/6/2007
Time:        4:39:35 PM
User:        N/A
Computer:    DEV-brad1
Description:
Event code: 3005
Event message: An unhandled exception has occurred.
Event time: 6/6/2007 4:39:35 PM
Event time (UTC): 6/6/2007 11:39:35 PM
Event ID: 45eb4075696844d69285a14804de3816
Event sequence: 3
Event occurrence: 1
Event detail code: 0

Application information:
   Application domain: 702995e8-2-128256467718720433
   Trust level: Full
   Application Virtual Path: /
   Application Path: C:\src\Location\
   Machine name: DEV-brad1

Process information:
   Process ID: 2400
   Process name: WebDev.WebServer.exe
   Account name: DOMAIN\brad

Exception information:
   Exception type: ArgumentException
   Exception message: Value does not fall within the expected range.

Request information:
   Request URL: http://localhost:4090/Pages/Default.aspx
   Request path: /Pages/Default.aspx
   User host address: 127.0.0.1
   User:
   Is authenticated: False
   Authentication Type:
   Thread account name: DOMAIN\brad

Thread information:
   Thread ID: 4
   Thread account name: DOMAIN\brad
   Is impersonating: False
   Stack trace:    at
DOMAIN.Location.Pages.Default.OnPreRender(EventArgs e) in C:\src
\Location\DOMAIN.Location\Pages\Default.aspx.cs:line 48
  at System.Web.UI.Control.PreRenderRecursiveInternal()
  at System.Web.UI.Page.ProcessRequestMain(Boolean
includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Custom event details:

For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.

I want to be able to map different exceptions on to Event ID's other
than 1309.  I found where someone figured out how to change the Event
Code (http://www.newtonsoft.com/blog/archive/2006/08/10/
WebRequestDetailedErrorEvent.aspx), but, our monitoring software keys
off of the Event ID, hence the need for more granularity than having
all exceptions end up with Event ID 1309.  Is this exception->Event ID
mapping hard-coded?  If configurable, can someone point me in the
right direction?  If I have to customize health monitoring, can you
point me at some sample code?  Any other ideas?

Thanks,
Brad