A combination of abs_path() and caller() works for me in one of my distributions:

use Cwd qw(abs_path);

my $script_path = abs_path((caller())[1]);

print "$script_path\n";
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Here's a full working example:

Package.pm:

package Package;

use strict;
use warnings;

use Cwd qw(abs_path);

sub import {
    my $path = abs_path((caller())[1]);
    print "$path\n";
}

1;
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Script:

use warnings;
use strict;

use lib '.';

use Package;
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