Have done most of the work in a separate custom wp plugin file.
Have copied it here. there's a couple bits that won't be applicable for every user of Registrations for Woocommerce plugin, but after you edit those (out?) you should be good to include it by default: https://gist.github.com/ajlowndes/7b7ba278815051c9d5a9b3b75e5d7dc9
Have done most of the work in a separate custom wp plugin file. Have copied it here. there's a couple bits that won't be applicable for every user of Registrations for Woocommerce plugin, but after you edit those (out?) you should be good to include it by default: https://gist.github.com/ajlowndes/7b7ba278815051c9d5a9b3b75e5d7dc9