The library you mention is now hosted on google see http://code.google.com/p/csharp-usb-hid-driver/
Perhaps these are helpful too:
- https://github.com/mikeobrien/HidLibrary
- http://www.usbhidnetclass.com/ (commercial) (usbhidnetclass.org previously)
- http://www.codeproject.com/KB/cs/USB_HID.aspx
- http://janaxelson.com/hidpage.htm
- http://www.codeproject.com/KB/system/HIDAche.aspx?q=C%23+and+USB+HID+Devices
- http://www.codeproject.com/Tips/530836/Csharp-USB-HID-Interface