To answer your second question first:

You will need to convert the date/time strings you have into epoch times, and pass them as the tick values, and then tell the program what format you want your labels to have. Here's some code that prints labels on the X-axis only for the first of each month.

my $cc = Chart::Clicker->new( width => 800, height => 300 );
my ( @k, @v, @x_tick_values );

# assumes data is in a hash keyed by dates as YYYYMMDD
for  my $datetime ( sort { $a <=> $b } keys %data ) {
    my ( $y, $m, $d ) = unpack("a4 a2 a2", $datetime);
    my $epoch = DateTime->new( year => $y, month => $m, day => $d )->e
+poch;
    push @k, $epoch;
    push @v, $data{ $datetime };
    push @x_tick_values, $epoch if $d eq '01';
}

my $series = Chart::Clicker::Data::Series->new(
    name   => 'Sales',
    keys   => \@k,
    values => \@v,
);

my $dataset = Chart::Clicker::Data::DataSet->new( series => [ $series 
+] );
$cc->add_to_datasets( $dataset );

$cc->title->text('Daily Report');
$cc->title->font->size( 20 );
$cc->title->padding->bottom( 5 );

my $context = $cc->get_context('default');
my $renderer = Chart::Clicker::Renderer::Line->new( opacity => .6 );
$renderer->brush->width( 2 );
$context->renderer( $renderer );

$context->domain_axis(
    Chart::Clicker::Axis::DateTime->new(
      format           => "%Y-%m", # Specify format here. I'm using "%
+Y-%m" since I 
                                   # output only one label per month
      ticks            => scalar keys %data,
      tick_values      => \@x_tick_values,
      position         => 'bottom',
      tick_label_angle => 0.78539816, # 45 deg in radians
      orientation      => 'vertical',
      fudge_amount     => .05,
    )
  );
  
  $context->range_axis->format( '%d' );
  $context->range_axis->fudge_amount( .02 );

  my $chart_path = "/path/to/your/chart.png";

  $cc->write_output( $chart_path );
[download]

As far as non-numeric axis labels: as I mentioned, you can't, directly. As the documentation for Chart::Clicker::Data::Series states:

Despite the name (keys and values) it is expected that all keys and values will be numeric. Values is pretty obvious, but it is important that keys also be numeric, as otherwise we'd have no idea how to order the data.

If you want to use text labels for your domain's see Chart::Clicker::Axis's tick_labels method.

... which reads:

The arrayref of labels to show for ticks on this Axis. This arrayref is consulted for every tick, in order. So placing a string at the zeroeth index will result in it being displayed on the zeroeth tick, etc, etc.

Hope this helps!