The Altspace SDK adds event bubbling to Three.js' events system. Simply include the SDK in your app and add a bubbling property to your event to take advantage of this feature.
AltspaceVR cursor events always make use of this bubbling shim.
Example
var parent = new THREE.Object3D();
parent.addEventListener('custom', function () {
console.log('received custom event');
});
var child = new THREE.Object3D();
parent.add(child);
child.dispatchEvent({type: 'custom', bubbles: true});
// Console log shows 'received custom event'