There is no automated method for incrementing the specified environment setting, so you may wish to consider writing a Python script that contains a nested loop to handle the extent tiling. For example, if your TIN's extent covers 1 km squared, and you have slices that divide it into 10 by 10, you can have a nested loop where the min x, min y, max x, and max y values are passed iteratively starting from the first block of 10 by 10 extent, and adding onto the extent values from there.