>>
>>You will need to set CommandType for the command object.
>>
>>For example,
>>
>>oleCmd.CommandType = CommandType.StoredProcedure
>
>When I originally tried that (and I just tried it again), it (the ExecuteNonQuery() ) fails with a "Unrecognized command verb." If I don't include it, it seems to work (except for the return value). I've checked the ID table and the table PK is definitely being incremented.

Try the following code..

OleConnection nConn = new OleConnection("Your Connection String");

OleCommand OleCMD = new OleCommand("NewId", nConn);
OleCMD.CommandType = CommandType.StoredProcedure;

SqlParameter myParm = OleCMD.Parameters.Add("@TableId", SqlDbType.NVarChar, 15);
myParm.Value = "User";

nConn.Open();

object oReturnValue = OleCMD.ExecuteScalar();

Console.WriteLine(oReturnValue.ToString())