There is no option to include the IP/hostname of the shopper on the merchant email receipts. It is on the View Orders screen as well as the in the order download information.
Or if it has to be via email, if you have ShopSite Pro and can add modules via the Order API feature (check with your host), then you could hire a programmer (assuming you aren't a programmer yourself) to create a custom module that can send you an additional email for each order that includes this information. Order API documentation is at:
http://www.shopsite.com/help/9.0/en-US/ ... r.api.html
-Loren