Rails - Sep 2005 - validates_uniqueness_of for a group

Hi 

I have 2 questions:

I want to validate that 3 fields together must be unique.  e.g -
first_name, last_name and birth_date.

To ensure 2 fields are unique as a group I can do this:

     validates_uniqueness_of	:first_name, :scope => "last_name"

1)  How do I add the third term so that all three are checked together?

Just to ensure my question is clear:
  
---John Smith DOB 4/4/1970 and John Smith DOB 4/4/1980 would be
allowed but not if all three fields matched.


2)  How do I set it to highlight all three fields but only output one
message like "First name, last name & birth date must be unique"

Thanks,
Dewey