The IRequest::BinaryRead method retrieves the current Request object in a safe array.
HRESULT BinaryRead(
VARIANT *pvarCountToRead, // pointer to a VARIANT that contains
// an integer value of the bytes to read
VARIANT *pvarReturn // pointer to a safe array that contains
// the bytes that were read by an HTTP Post
);
A SafeArray is an array that contains information about the number of dimensions and the bounds of its dimensions.