XNA Real time texture 2-D deformation

Need an XNA guru to help us with specific XNA 4.0 functionality. Project will provide 2 Texture 2-D objects. One Texture2D will start as flat concrete texture. We'll call this the "Concrete" texture. The other texture will be the same size and will be black and varying shades of white. The more white (#ffffff) the color is the harder the "pressure" is represented. That is, the darker shades should deform the surface less than the lighter shades. With #000000 performing no deformation whatsoever. The shape represented by the white can be anything (hand, pen tip, just about anything). The trick is that we'll want to do multiple passes, perserving deformation between each call. So if we did a 2nd call the deformations would press "further" down into the concrete texture. We can't measure pressure on this device so we're substituting time for pressure. The longer an object interacts with the application the deeper the deformation is. The size of the texture 2D's are usually 900 pixels wide by 1020 high but this can change and your class should be able to handle different sizes. We'll guarntee the the 2 textures inputed are the same size and can remain the same size for the entire lifecycle of the application (they won't change size unless we do a new build). Optimally we'd like you to write a class that exposes to us a function like this: public Texture2D Deform(Texture2D concrete, Texture2d deformation, bool resetDeformation) { } Delivery will be a C# class that works with XNA 4.0 or higher that performs the above described function.