After researching this extensively, there does not appear to be a way to modify the Tool Tip that displays when hovering over an event.  This question has been asked by several users over the last year and no one ever responds.

This Tool Tip appears to be different than standard Tool Tips, which can easily be modified by finding the correct .help entry in the appropriate resource file (.resx).  This tootip apparently does not pull info/instructions from the .resx file.  I'm not sure how it knows to display the Dates/Descriptions from the event.  Perhaps this is embedded in a .vb file.  If anyone (Alan??) can shed some light on this, that would be wonderful.  At least point us in the right direction - I'm willing to do some legwork.