To load a color image from a file for the icon:

my $mw = Tkx::widget->new('.');

my $img = Tkx::image_create_photo(-file => 'icon.gif');
$mw->g_wm_iconphoto($img);
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If you have embedded data to use instead of a file (note the -data instead of -file in create_photo):

#Pack hardcoded GIF bytes:
my $icon = pack('C*' ,71,73,70,56,57,97,64,0,64,0,247,0,0,84,186, ...
my $mw = Tkx::widget->new('.');

my $img = Tkx::image_create_photo(-data => $icon);
$mw->g_wm_iconphoto($img);
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