i think you can simply add socket.io to your package.json and install the typings for socket io -->
https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/socket.io/socket.io.d.ts
install the typings module: npm install -g typings
after that you can install the typings for socket.io typings install
typings install socket.io-client --save --ambient
if “–ambient” does not work any more your can try “–global” instead