This layout has the clean mod already built in. There is also a thread about adding an lfo mod. It works great clean, but because the signal isn't as hot, the modulations aren't quite as crazy. Honestly they still are pretty wild, even with low output single coils and the fact that there's no fuzz there makes them much clearer and more prominent, but if you boost the level, the pitch shifting goes nuts, so its nice to have that option, too. The buffer is probably just to keep the signal strength up.
I got around that by just using a clean boost. I'm not good enough (or rather I'm too lazy to try) to make a layout incorporating a buffer or clean boost, so I just built a separate one on another board and wired them together.