are you 100% sure you've downloaded the right driver from lenovo's website for your PC? installing the "Intel Chipset Driver for Microsoft Windows 8 (32-bit, 64-bit) - Lenovo G470" (for your appropriate windows version of course) should install intel HD graphics.
Then you should be able to install the "AMD Graphics Driver (Discrete) for Microsoft Windows 8 (32-bit, 64-bit) - Lenovo G470" followed by "AMD Switchable Graphics Driver (Muxless) for Microsoft Windows 8 (32-bit, 64-bit) - Lenovo G470", both choosing the appropriate one for your OS.