To my knowledge there is no pure-Perl implentation of Oracle's network protocols.
DBD::Oracle makes use of a locally-installed Oracle client library (which I suspect probably carries licensing issues) to do the actual work.
You may have some luck getting ODBC to work. I believe there are some freely available ODBC implementations out there, though I don't know if any of those are pure-Perl either.
You say you've gone through the process of trying to install non-Perl components (I'm assuming modules that are implemented at least partially in C) and have failed. I'm not sure that it's going to be easier for you to find an all-Perl solution this or if you just need to bite the bullet and solve whatever fundamental problem that exists with your system that is making it difficult for you to install C-based Perl modules.
