the sound plugins can be done in any language in what a plugin can be done, ie: VB, C++, VB.NET, C#, Delphi, Asm, etc... however they're usually done in VB and C++ (the most used ones). I don't know all the sound plugins, but Audiator, for example, let you configure the sounds and you don't need to use a resource editor to change them.
To change Plus sounds you have to use an editor, however
- that would be illegal (so i won't tell you how to do it), and
- only you would hear the modified sounds