use strict;
use warnings;
use Text::xSV;

my $csv = Text::xSV->new(
   sep    => ':',
   fh     => *DATA,
   filter => sub {($_ = shift) =~ s/\\{2}/\\/g;$_}
);
$csv->bind_fields(qw(foo bar baz qux));

while ($csv->get_row()) {
   print $csv->extract('qux'), "\n";
}

__DATA__
0005:A:A2:\\\\string 04\\\\
0005:A:A2:\\\string 04\\\\
0005:A:A2:\\string 04\\\\
0005:A:A2:\string 04\\\\