Custom Elements on BpmnViewer

We are using BpmnViewer to show the bpmn diagram in readonly mode.
But we use custom elements in our designs.

Is it possible to show these custom diagrams using BpmnViewer ?
Could you please provide link or any example bpmnviewer using custom renderer.

Yes you can. What keeps you from showing them in the viewer (when you already can show them in the modeler)?