PredicateBuilder/LINQ Encapsulate predicates, DI

Question

I've started to notice that i my predicate building code looks similar. That's a sign to refactor it. Let's look at the code.

    var predicate = PredicateBuilder.False<ArticleLikeInfo>();

    // Under the covers it will get Guid from a cookie (one way to track a user)
    Guid? key = _userKeyService.GetKey();
    if (key.HasValue)
    {
        predicate = predicate.OrElse(x => x.UserKey == key.Value);
    }

    String ip = Request.UserHostAddress;
    if (!String.IsNullOrEmpty(ip))
    {
        predicate = predicate.OrElse(x => x.UserIp == ip);
    }

    UserInfo user = _userSessionService.CurrentUser();
    if (user != null)
    {
        predicate = predicate.OrElse(x => x.UserId == user.Id);
    }

    bool hasVoted = _articleService.GetLikes().Where(x => x.ArticleId == m.Id)
                                              .Where(predicate)
                                              .Any();

This code runs when i need to check if the user has pressed "like button" on the article. To trace the user i use

1. Spy guid key from cookie
2. Ip Address
3. UserId if he has logged in

The same code runs when i issue ajax call to insert "like vote" for an article in the database.

So i would like to encapsulate it. My first idea was to opt for extensions method approach, but i dont like it, since i will have to resort to ServiceLocator pattern to get references to services like that

IUserKeyService service = ServiceLocator.Current.GetInstance<IUserKeyService>();

I feel that would be a bad design, since its not testable. I would like to have a class which is reusable and at the same time can be controlled by DI container. A class which i can inject dependencies into. Is it possible ?