You will have a very hard time because it has its own script (though I guess you could use C#) and it's very opinionated about lots of things like the node graph, etc.
Godot has support for many programming languages [0] through 'GDNative' which generally lets you access the API through any programming language that can bind to C++. I see that there is D support [1] but I have no idea how robust it is.