Injecting new Custom Actions

I have an application that gets installed via MSI and updated with wyUpdate. Presently we have a new update that includes a service and a system tray app as part of the core application. However since the files are copied and the service registered in code there are no custom actions in place to handle an uninstall of the application from the original add/remove programs.

My question is are there any thoughts on how to handle this? Is there a way to inject a custom action so that we can tie into the uninstall of the original application to get the service uninstalled as well?

Thanks,Chris