Concerning the alarm data, I think you should use Event Frames to store this kind of information. The upcoming version of PI Notification 2016 actually uses Event Frames under the hood to store the notifications that were generated. From my understanding, PI Coresight already allows you to view Event Frames and PI data together on a trend. So, this is the simple solution.
If you want to use it in PI ProcessBook, it would be more complicated. PI ProcessBook does not have direct access to event frames for now. Therefore, you need to show Event Frames data through AF attributes. There are ways for you to do that:
1)Create a custom data reference that you can use in a new attribute that will get event frames data.
2)Create a Windows Service with PI AF SDK that will keep sending Event Frames data to the PI Data Archive. You would also use a new attribute but with PI Point Data Reference instead.
Let me know if this helps you!