This should theoretically be easily accomplished by changing the action on the form to point to your domain.
However if you plan to authenticate entries, you would probably have to make them use the default user, since the user won't be logging in and there wouldn't be a user session stored in your database.
However if you plan to authenticate entries, you would probably have to make them use the default user, since the user won't be logging in and there wouldn't be a user session stored in your database.