How to swap the method bodies of two functions

I'm in the process of writing some auto generating code based from (not on) existing code using reflection. If I can give a scenario think of it as what Im doing as writing a VS extension that will convert Winforms to XAML.
Now I've gotten to the point where I need to be able to copy the method bodies. Reason being the "ItemClick" events signatures are slightly different and I cannot just assign it from Winforms to XAML. I am able to generate the signature. But how do I go about copying the method bodies across? Remember the purpose of it all is to in the end generate C# code (as I have literally hundreds of files I need to convert).