How do I authenticate using Polymer's iron-ajax

Has anyone done this?  I tried sending it as a param based on the nodejs sample but it doesn't seem to work.

<template is="dom-bind" id="app">
    <iron-ajax auto
               url="https://mhchelpdesk.freshdesk.com/api/v2/tickets"
               params='{ user: apikeyhere, pass: "X", sendImmediately: true }'
               handle-as="json"
               last-response="{{ajaxResponse}}"></iron-ajax>

    <template is="dom-repeat" items="[[ajaxResponse.items]]">
        <mhc-ticket ticket-id="[[item.id]]"></mhc-ticket>
    </template>

</template>