Call stored proc on ORACLE via MS-SQL

I wonder if anybody had successfully linked MSSQL2000 Server to an Oracle and called a stored proc on it via MSSQL. I'm very interested in the ability (declared in the Oracle documentation) to convert input sproc's parameters of type REF CURSOR into the datasets, or at least how to call a regular stored proc with usual scalar parameters.

Maximum that I could do is to execute a query via the ODBC provider. I cannot call a procedure using neither MS nor Oracle's OLEDB provider, Oracle's one cannot execute even the simpliest query with the following error:

Could not execute query against OLE DB provider 'OraOLEDB.Oracle'. OLE DB error trace [OLE/DB Provider 'OraOLEDB.Oracle' ICommandText::Execute returned 0x80004002]. Received on Fri Mar 14 2003 - 05:39:14 CST