WPF XAML developer required for mature, existing desktop app

We need an extra pair of hands to help develop the screens of an existing commercial WPF app. We use the MVVM pattern with Caliburn Micro framework but that side of it is trivial to learn. We are looking for someone with good XAML skills who can also write C# view models that contain the screen logic. The data layer is provided by services that we maintain. We have all the XAML styles in place so the task is mainly working with us to fulfil our specifications and keep the same look and feel as the rest of the app.

We estimate that this part of the project will require 3-4 weeks work but, if it is successful, we should have more in future.