MinGW compiler is here: http://www.mingw.org/download.shtml#hdr2
in reply to Re: A guide to installing modules for Win32
in thread A guide to installing modules for Win32
But mingw.org provide only a 32-bit compiler, and the 64-bit ActivePerl would need a 64-bit compiler, such as the one offered by the mingw64 project (a different vendor than mingw.org).
And even then, in order to get this 64-bit compiler working with ActivePerl, I found it necessary to do some hacking to lib/Config_heavy.pl, lib/ActivePerl/Config.pm and lib/ExtUtils/MM_Win32.pm.
You're right about dmake - however, I'm not sure that there's any problem with nmake itself.