var xmlTemplate = '<your xml template here>';

var templateRenderer = render.create();
templateRenderer.templateContent = xmlTemplate;

templateRenderer.addRecord({
  templateName: 'record',
  record: record.load({
    type: record.Type.INVOICE,
    id: 1234,
  });
});

renderer.addCustomDataSource({
  format: render.DataSource.OBJECT,
  alias: 'customData',
  data: { /* your custom data here */ },
});

var pdf = renderer.renderAsPdf();