Update A Users Birthday - Nightly as Task

[gpc10347]

I know I'll probably be quickly told that I must gnarfle the garthok for even asking such a silly question, but (there's always a but), I'd like to create a Scheduled Task to run specifically to update a users date of birth to the day coming (Each day would then be the users' birthday)...

I gather from reading the manual, I'd need to set the task to run before the Birthday Message task and all that for the following day. I also need to create a PHP file to update the user record by the userID -

The questions I have are regarding where one would put the PHP file in order to prevent a bot or user from being able to run in (inadvertantly) and, if anyone has a snippet that would do this safely...

(Call it Groudhog Day...)
Thanks for any assistance with this rather oddball inquiry