C:\>type test.pl

my $line = 'C:\just\work\split\fine';
@data = split /\\/, $line;
$new = join "\\", @data[0,3,2,4];
print "\nHad => $line\n", "Got => $new\n\n";

C:\>perl test.pl

Had => C:\just\work\split\fine
Got => C:\split\work\fine

C:\>