To call a script, you can make it as handler and put it at (as of 1.1.6.2) the directory named handlers/page/, ie smthg like handlers/page/cron.changemail.php

Then to call the function, use url of the type http://yourdomain.com/yourwikkadir/HomePage/cron.changemail

(In your example :
lynx -dump 'http://yourdomain.com/wikka_changemail/HomePage/cron.changemail)

Thanks for the suggestion. I suspected there must be something like this, just wasn't sure how to configure it. I'll keep this in mind for the future.