Add the data array in code and then you can reference it in 'set' event:
<div data-role="fieldcontain">
<label for="cf" data-i18n="config.localelabel"></label>
<input name="cf" type="date" data-role="datebox" id="cf" data-options='{"mode": "customflip",
"useNewStyle": false,
"overrideStyleClass": "ui-icon-dice",
"useButton":false,
"useFocus" : true
}' />
In code create a global variable called selectdata that is the array of values:
var selectdata = ["Italiano","English","Espanol","Deutsch","Francais","русский"];
jQuery.extend(jQuery.mobile.datebox.prototype.options, {
'customData': [{
'input': true,
'name': '',
'data': selectdata
}],
"useHeader": false,
"overrideCustomSet": "OK"
});
$('#cf').on('datebox', function (e, p) {
if (p.method === 'set') {
e.stopImmediatePropagation();
$(this).val(selectdata[p.value]);
}
});