When I try to build the two required modules alone, I can't get a succcessful installation.

well, show us the errors of installing the 2 required modules. Unless you mean you installed the 2 modules successfully but still no joy for the target module. In which case, check your include dirs or whether you used different perl versions (via perlbrew), etc. etc. Check if the path ~/build/perl-testing-libs/lib/perl5 contains the 2 dependencies. Should that -L contain lib/perl5? I am not acquainted with this option.