The simplest way would be to create a standard HTML page, however you like, with your image inserted normally. Then use the .CreateMHTMLBody method to let CDO create the message from the file and send it.
I find now that W2k and up are using the standard CDO, one does not need any 3rd party addons. I have a 1000+ page book, oddly enough published by Wrox :), that only covers Messaging, mostly with CDO. It is amazing what you can do, as I am finding out.