I will try and help you further with this when I have time but basically I think you would need to do the following to get this to work:
1) create a csmodule that monitors the new post event (of type comment) and check they are on an application of type wiki in the code also.
2) add a custom email provider class that will create a new email (it will use the template below).
3) create a new email template in the /Languages/Resources/En-us/Email/ folder with the contents of your notification email.
This should then check for new comments in wikis every time one is made and then send an email to whoever you specify.
Hope this helps.