I had a look at the HTML 5 geolocation feature and on my laptop, with no built-in GPS, I couldn’t get a precise location. This is based on the internet provider, and in my case gave a result hundred of miles away from my location.
We do have some customers using real GPS position (check this thread) from either an Android device or an iPad. This is the best option for moving devices.
In your case, since you are talking about a kiosk, I guess it has a fixed position, no? You could enter its position (latitude/longitude) in an Excel file when setting it up.
Can you tell me more about the usage scenario for this Chromebox?