odp.nett 11g IOracleCustomType equivalent in 10g odp.net

Question

 The type or namespace name 'IOracleCustomType' could not be found (are you missing a using directive or an assembly reference?)
Getting the above error as i dont see any IOracleCustomType in Oracle.DataAccess.Types namespace in odp.net 10g but its there in 11g odp.net please let me know what can i do if i want to use 10g odp.net