Often I find the need to dynamically specify the order by for a LINQ to SQL query.  I came across a very nice example of this here. 

I needed to use this technique with a CSLA class, so I needed to call it in a sligthly different manner than the way explained in the article.  I was grouping information and needed to then dynamically set the order by and finally place the results into a CSLA read only list.

I accomplished this as follows:

1. First I specified my LINQ query and selected the results into an annonymous type and placed into a variable (var data = ...)
   
2. Next, called my OrderBy extension method on the LINQ query created in #1
   
   var ordered = data.OrderBy(criteria.OrderByProperty, criteria.OrderByDesc);
   
   
   The criteria object is the typical pattern used in CSLA to pass data to your data access methods such as fetch.
   
3. Finally, I selected the data elements into my CSLA list item, and add to the parent list object
   
   var selected = ordered.Select(a => MyCslaListItem.GetMyCslaListItem(a.Id, a.Name, a.Email, ...));
   this.AddRange(selected);

I understand I could do this in fewer steps, but am leaving as it to explicitly outline the approach taken.