Read a 6DOF IMU (Gyro + Accelerometer) using PRU - Beaglebone black
I would highly recommend simply using the beagle bone's I2C library's to do this. The library should allow you to set the I2C speed up to 400kHz, which is also known as "fast mode".

One of the things to consider when determining the I2C bus speed is how much data you actually need to move across it. If you are only going to be looking at two sensors like the ones you linked, chances are having a really high I2C bus speed will not make difference anyways. I can't seem to clearly find the data rate for the gyro but it appears that the accelerometer only produces new data at a rate of 3.2kHz. Using a multi-byte read for the device even at the normal 100kHz you will most likely be able to read data faster then the device can measure a new value. Running at higher speeds starts to show benefits when you have many devices communicating on the bus or devices that operate at a high speed themselves.