Why to connect via ODBC to Presentation Server? You can connect via ODBC to BI Server but the Presentation Server I don't think it has any ODBC interface ...
+1 to Gianni. ODBC is more for access to the Oracle BI Server rather than the presentation server.
OBIPS access is more often done via Web Services if you need outside access due to the graphical nature of the OBIPS plus also the Action Framework which is task based and not "get-me-some-data-out" ODBC