Override route values with user preferences values

I have a route which has default values f开发者_开发知识库or a search, e.g. Sort=new and show=all

In my web app, each authenticated user has their own preferences where they can set their own default search criteria.

How do I make the route use the users values instead of the defaults specified in global.asax? E.g. Sort=cost and show=thisweek

I've tried a number of different things so far but to no avail

I managed to get what I wanted using the BaseController and overridden Execute method.