Module::Build didn't work on AIX? I thought a major point of Module::Build's approach was to do things in Perl where stuff "just works" across many platforms.
Its not Perl its XS and C compiling. Everybody's compilers work differently and everybody's systems have things in different places and everybody has slightly different things broken. And once you've figured that all out you need to try it again for the next older version. And the next. And the next. Its a nightmare.
MakeMaker has figured this out over the years but the result is a tangled mess of code. Ken has written ExtUtils::CBuilder and ExtUtils::ParseXS which is a modularization of the XS and C voodoo from MakeMaker but its slow going. Don't think of it so much as mining MakeMaker for information as painfully extracting precious gems and oils from tar sand.
FWIW both ExtUtils::CBuilder and ExtUtils::ParseXS (and its improved xsubpp) have just gone into 5.9.x today.