While possible, import into P6 via ODBC it is strongly discouraged and also required a through knowledge of the related tables. Primavera maintenance can be voided should it be discovered that imports of this nature have be used by a client.
That said, use of the privuser account is the preferred user/schema to be used. This has less dba level rights, e.g., table drops, and therefore a bit safer.
Search the Oracle Primavera Knowledgebase and you will find some Excel worksheet that use the Software Developer Kit (SDK) for imports and exports. Generally the java API or Web Services API are recommended for this type of functionality.