This is similar to Roger's.

$escaped_str = <<'EOT'; 
Xa\X\\bXc\\XdX
EOT
chomp $escaped_str;

my @array = ();
my $escaped = 0;
my $count = 0;

for (split //, $escaped_str)    {
    if (!$escaped && $_ eq 'X') { $count++; next; }
    $array[$count] .= $_;
    $escaped = ($_ eq "\\" && !$escaped) ? 1 : 0;
}

print "(",join(':',@array),")";
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