Okay, I tried that Math-Int128 package and it did install successfully on my Active Perl 5.16.3, 64-bit. Thanks for that.

However, I come back to the same problem: the last package I need to install is MaxMind::DB::Reader, and it requires version 0.12 of Net::Works. The Active repo has version 0.01 so I use cpan to try and install Net::Works 0.12 and dmake barfs on the same `inet_pton' errors:

C:\apps\Perl64\cpan\build\Net-Works-0.12-8Cw8vA>dmake test
C:\apps\Perl64\bin\perl.exe "-MExtUtils::Command::MM" "-e" "test_harne
+ss(0, 'blib\lib', 'blib\arch')" t/*.t
t/Address.t ................ Socket::inet_pton not implemented on this
+ architecture at C:\apps\Perl64\cpan\build\Net-Wor
ks-0.12-8Cw8vA\blib\lib/Net/Works/Address.pm line 67.
t/Address.t ................ Dubious, test returned 255 (wstat 65280, 
+0xff00)
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I am using the gcc (rubenvb-4.5.4) and dmake (4.12-20090907) provided by Active's PPM.