i'm going to hate myself for saying this:
you could redirect all requests for your home page to a new url - say home.html or default.aspx or what have you - and exclude that url from crawling in robots.txt.
it might even be confusing enough if you used a 302 status code.
that meets the "letter of the law" so to speak.
it certainly doesn't address the "completely destroying the site's SE traffic" side of things.
i'm pretty sure no matter if, where or how you redirect and then block your home page from crawling that turns your home page into a link sink.
i can't see anything good resulting.
are you moving to a new domain or subdomain?