Claptrap can go die in a fire.
To compile the SDK you'll need the following:
- Microsoft Visual Studio 2012 (2010 will work if you change the platform toolset and the version in the SLN file)
- Windows SDK (I'm currently using 8.0)
- DirectX SDK (Download Link)
Just open up the solution file in the build folder and compile in Debug mode. Hopefully it compiles, you're pretty lucky if it does.
Running the SDK at the moment is still a little bit involed, and will not work correctly with the Steam version. I'll be improving the launcher to make things a bit easier.
To compile, open the solution and build it as you normally would. After you've done that, copy the lua folder in the root directory of the repository into the build\Debug or build\Release directory.
After you've compiled the SDK, just open up bin\Debug\Launcher.exe, make sure it has the right location for Borderlands2.exe and click 'Launch Game'.
After it's injected into the game, you'll have a Windows console open up and if you press your in-game console key, you should be able to see some various messages in that console too.
Here are some useful resources.