Here's my notes from a540. This was found by looking for various incarnations of RegisterEventProcedure. Not all are confirmed. They are grouped by which function registers them. In some cases it isn't just a simple table in ROM, there's multiple levels of functions, and sometimes the list of event procs comes from RAM, etc.
Note, the eventprocs available will depend on the camera. The list above is from a Digic II vxwork camera, so modern cameras will be quite different. Even where functions have the same name, the expected arguments may be different. Also not that it is possible to disable or destroy your camera using them. In my notes
dragons indicates ones I expected to be dangerous for one reason or another, but that doesn't mean the others are safe!
http://chdk.wikia.com/wiki/User:ReyalP/EventProcNotes
