Hi,
As regards building Net-SSLeay-1.68 on Windows, the first thing I always do is remove the provided Makefile.PL.
(Coming to grips with the crippling conditions imposed by inc::Module::Install is something I most definitely do wish to avoid.)

I replace that Makefile.PL with one that contains:

use ExtUtils::MakeMaker;

WriteMakefile(
    'NAME'             => 'Net::SSLeay',
    'VERSION_FROM'     => 'lib/Net/SSLeay.pm',
    'LIBS'             => ['-lssl -lcrypto -lcrypt32 -lz'],
);
[download]

(I can't recall why "-lcrypt32" is there ... I strongly suspect it's not needed, but it's not causing any breakage.
And you might not need the "-lz" either.)

However, that works for me only because the required libraries and headers are being found by default. That is, they're located in directories that are automatically searched.
If your openssl libraries and headers are in directories that are not automatically searched, then the Makefile.PL needs to specify something extra.
Let's say that your openssl headers are in C:/someplace/include/openssl and that your openssl libraries are in C:/someplace/lib, then the Makefile.PL would need to be something like:

use ExtUtils::MakeMaker;

WriteMakefile(
    'NAME'             => 'Net::SSLeay',
    'VERSION_FROM'     => 'lib/Net/SSLeay.pm',
    'INC'              => '-IC:/someplace/include',
    'LIBS'             => ['-LC:/someplace/lib -lssl -lcrypto -lcrypt3
+2 -lz'],
);
[download]

That works fine for me, except that on some 64-bit builds of perl I get a t/ocsp.t failure (which I ignore) during the "dmake test" stage.
If that approach does not work for you, I'd be wanting to see the error messages you're getting, the full path to your openssl headers & libraries, and the actual Makefile.PL that was run.

Cheers,
Rob