Basically, there should be nothing special (due to EF) when implementing the specification pattern. You implement the specifications as separate classes, which work with your domain model.
You can find lots of articles or webcasts about the specification pattern, and even some which use EF, e.g. here and here.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…