I have currently a joomla3 install, and I want to overwrite the server-side validation, and the clientside validation of the username (I only want users to be able to sign up with a phonenumber)... How can I overwrite these two things, most easily?
Thanks in advance :)
EDIT: Oh yeah, and what I might have forgotten to mention, is that I am working on a previous joomla1.5 install, we are migrating to joomla3.0, and a lot of bad conventions (like overwriting core files, copying of entire functions, and other code) have been used... I am merely trying to get on with the migration, without having to edit alot of stuff...
So I am trying to maintain the structure, that the username, is the phonenumber, to not have to change alot of things, that can't be automated