the wizard will not do this for you, but if you add two email address form elements to the form, you can change this after the form is created.
Once you have created the form, go to the server behaviors panel and double click the Server Validations server behavior. Select the Like entry validation type. Click the lightning bolt next to server variable and select the first email address form element. then click the plus button to add it to the list of validations. This will prompt you to select the comparison, click the lightning bolt again and select the second email address form element.