In Master PerlTk Chapeter23, pTk Potpourri, it discusses how to make custom cursors:

Besides a built-in cursor name, the -cursor option also accepts a cursor specification, which is an array reference of four elements: an X11 bitmap (XBM) filename, a mask filename, and foreground and background colors.

on unix/linux it would look like

my $cursor = [qw/@mouse.xbm mouse.mask brown white/];
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The X11/cursorfont.h file contains the names, tracking it down from there is left to you.

Here is code from the MPTk's sample code:

#!/usr/bin/perl -w
use Tk;
use strict;

my $mw = MainWindow->new;
my $c = $mw->Canvas->grid;
$c->configure(-cursor =>
 ['@images/trans_cur.xbm', 'images/trans_cur.msk', 'black', 'white']);

$c->CanvasBind('<Motion>' => sub {
    my($c) = @_;
    my($x, $y) = ($Tk::event->x, $Tk::event->y);
    print "cursor at canvas coordinate ($x,$y)\n";
});

MainLoop;
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It is supposed to give you a transparent cursor, but it shows the idea. If you want the images, track them down on the Mptk website, under Chapter code samples.