The solution that I use is to write a function that returns a hash reference that is tied. Like this:

use Tie::IxHash
sub ordered_hash_ref {
    tie my %hash, 'Tie::IxHash', @_;
    return \%hash;
}

# time passes...

tie my %data, 'Tie::IxHash',
    1 => ordered_hash_ref(
             6 => ordered_hash_ref(
                      width     => 53,
                      len       => 16,
                      width_arr => [ 53 ],
                      mems      => 1,
                      rows      => 1
                      mux       => 4,
                      len_arr   => [ 16 ],
                      cols      => 1,
            ),
    ),
    ;
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This is nice if you like having your nested data structures declared compactly, albeit at the cost of having to put the function calls in there.