I don't know if this will help you as even after reading some of the comments it is not clear exactly what you are trying to achived.
You don't need to install all of Oracle to use DBD::Oracle. You can just install Instant Client in which you need the client, sdk and sqlplus which are all downloadable separately and are fairly small.
UPDATE: You can access Oracle without installing Oracle's client libraries. There are so called wire-protocol ODBC drivers for Oracle from various companies. Of course, you have to install them.