Apologies for the delayed response here.
Accelerometer data is stored in MyGeotab as part of the StatusData dataset.
If you are looking to retrieve a accelerometer on any kind of interval or stream then the way to do this is with the GetFeed call.
The GetFeed should be run against the StatusData object. You will then need to parse through the results and keep only what you desire, if that is just the Accelerometer data then those would be the only records you would keep.