It goes something like this:

sub AUTOLOAD {
  my $self = $_[ 0 ];
  ( my $name = our $AUTOLOAD ) =~ s/.*:://;
  return if $name eq 'DESTROTY';
  die "Unknown field: $name" unless exists $OK_FIELDS{ $name };
  return @_ ? $self->{ $name } = shift : $self->{ $name };
}
[download]

As you can infer from the above, this version assumes that the instances of this class are implemented as hash refs. However, I don't like using AUTOLOAD when I have a lot of inheritance going on (but then, I don't use inheritance much).

I've seen many descriptions of this technique. You can find one in this section of perltoot. Also, The Perl Cookbook, the Alpaca book, Object Oriented Perl discuss the use of AUTOLOAD to generate accessors. I'm sure this list is far from exhaustive.