Validation of multiple form elements

Hi All

First af all, I'm new in Phalcon so i'm still learning to fly, so sorry if the question is not so precise.

I'm trying to create a form, where a user can type in an url for a webshop, together with api credentials user name and psw. I can add validators to each of the elements i the form, like PresenceOf and make a save to the database. I would like to construct a validator that validates the api credentials and return true/false. Is it possible to construct a validator the takes more than one input argument and add it directly to a form?

Please give suggestions for other possible ways to go, if this approach is not optimal.

Thanks in advance