my %myDict = map { unpack "CxA*" } unpack "(xCXX /A)*", $inputString;

NB: unpack TEMPLATE only unpacks the default scalar  $_ with Perl versions 5.10 and above. Prior to 5.10, use
    my %myDict = map { unpack "CxA*", $_ } unpack "(xCXX /A)*", $inputString;