You could use imagemap_dump together with GD, for example ;

#!perl
use strict;
use Data::Dump 'pp';
use Chart::Points;
use GD;
my $obj = Chart::Points->new ( 400,300 );
$obj->{'imagemap'}=1;
my @labels = ('A','B','C');
$obj->set ('legend_labels' => \@labels);
$obj->add_pt ('foo', 1,3,2);
$obj->add_pt ('bar', 4,5,6);

# create GD image
my $img = GD::Image->new($obj->scalar_png);
my $imagemap_data = $obj->imagemap_dump();
#pp $imagemap_data;

# add labels
my $black = $img->colorAllocate(0,0,0); 
for my $i (1..3){
  for my $j (0..1){
    my $text = $labels[$i-1];
    my ($x,$y)  = @{$imagemap_data->[$i][$j]};
    $img->string(gdSmallFont,$x-10,$y-10,$text,$black);
  }
}

open (PNG,'>','chart.png') or die "$!";
binmode PNG;
print PNG $img->png;
close PNG;
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poj