There use to be the ability to create Vertical Event Points. This appears to have been removed in that the Event Point List is now singular and tied to the Horizontal Alignment. The old capability (now removed) allowed things to be annotated in the vertical without annotating in the horizontal and vice versa.
I would guess that the method to do this relies in the name of the Event Point List. You can accomplish this, but the workflow is not as straight forward. For instance, you could create a Vertical Event Point List named Vertical, and then set up the Vertical Annotation to annotate event points from the Vertical event point list... On one hand more robust, on the other, more setup for the end user....