I'm afraid it wouldn't be possible. I just looked it up and it seems that you would have to host this software on your own web server. According to the system requirements information I found, this solution requires that you have full access to your web server, can install & configure MySQL and Perl scripts on that server and interface a mail transfer agent directly. So, the bottom line is, you couldn't really properly integrate this with Website Maker. Maybe you could go for a mailing list manager solution that will provide the hosting for you, e.g. Bravenet's mailing list feature (kinda as a very basic but free solution).