Is it possible to encrypt it in the same manner as the existing forum password (I'm assuming that's fairly well encrypted). My concern is that the same username/password combination used on some of the SMS portals are the same one the users would enter for their billing so must be protected.
Please bear in mind with any reply that I'm a PHP n00b, although I have a sound programming knowledge of other languages so have some sense.
Also is it not possible to refer to the custom field by name?