What's the proper way of parameterizing an order by clause in ADO.NET ?

Sometimes there's a need to order by 2 columns, while the default is ordering on just 1 column, and sometimes you'll just want to change ASC to DEC. 
Is it considered ok to just use string concatenating in such cases (provided the input doesn't come from the user directly, but just a lookup of more or less hardcoded values in the code)