hi!
i wouldn't use an execute SQL task for that (don't even know if that is possible at all).
create and active-x script task instead. connect to your ORACLE database by using standard ADO (MS MDAC) library. issue your command by using an ADO command object capturing the return value of a, say ORACLE function into your global variable. close your connection.
very brief example of VBScript code:
dim conn, cmd
set conn = CreateObject("ADODB.Connection")
conn.Open( <connection string> )
set cmd = CreateObject("ADODB.Command")
cmd.ActiveConnection = conn
cmd.CommandText = <your ORACLE command>
cmd.Execute
DTSGlobalVariables( <your global var> ) = <output param/return value of command>
conn.Close
cmd = Nothing
conn = Nothing
for further information on ADO refer to MSDN.
best regards, chris.