@sparklos, from what I can see from the datasheet, the frequency output range of the device is 3.2-200Hz which is slow enough do measure using polling depending on what else you are doing in your loop() function. You could also use interrupts. I found what appears to be a great Arduino frequency counter library that can operate in both polling and interrupt mode. It should be straight forward to port to the Spark (which I can do if you wish).
As for powering the device, you will need a voltage regulator to get either 5v or 3.3v to power the Spark from the 8-35V you use for the sensor. The tricky part will be level shifting the 8-35V (depending on the supply voltage) output to 3.3v. This calls for high voltage to low voltage level shifter between the device and the Spark. Some research is required to identify the correct part. 