I'm no expert, but if I were you I'd use one bean for the entire table, but have whatever structure is most logical in your value objects. Then, do the mapping in the getVO/setVO methods on your bean. I'd imagine it'll be much easier to do the mapping there.
You couldn't use CMR to do your daybean/timebean mapping, since (AFAIK) all CMR implementations require two tables with a foreign key-type attribute on one or both of them. It seems to me that the basic usual
philosophy 'one entity bean maps onto one table'.
More on Sun's view of Value Objects is
here, though I'm not sure that'll be of that much use.
-Tim