So, I've modified the beginning of the Printer::Unix file in the standard Printer module (which, BTW, I feel so inadequate to modify a CPAN module):

use Env qw(PRINTER LPDEST NPRINTER NGPRINTER PATH);
#added the two following lines
$ENV{'PATH'}='/usr/local/sbin';
delete @ENV{'IFS', 'CDPATH', 'ENV', 'BASH_ENV'};

############################################################
sub list_printers {
...
[download]

I've verified the location permissions. Anything I set it to is non-world writable, but still tanks.

I don't know if it's relevant, but I found this. It appears to be very similar to what I'm experiencing, however, with a different module. Of course the fix given in that post is specific to the MIME::Lite module...not helping here.

So, I've modified the beginning of the Printer::Unix file in the standard Printer module (which, BTW, I feel so inadequate to modify a CPAN module):

Well, you're supposed to modify your program ...... and error messages don't come without line numbers