You will need work the interval slider in terms of [`AbsoluteTime`](http://reference.wolfram.com/mathematica/ref/AbsoluteTime.html) because the slider only works with numeric objects. Here is a demonstration.

    With[{
      min0 = AbsoluteTime @ DateObject[{2015, 3, 8, 10, 0, 0.}],
      max0 = AbsoluteTime @ DateObject[{2015, 3, 8, 12, 30, 0.}],
      minT = AbsoluteTime @ DateObject[{2015, 3, 8, 0, 0, 0.}],
      maxT = AbsoluteTime @ DateObject[{2015, 3, 8, 22, 30, 0.}]}, 
      Manipulate[
        DateString /@ span,
        {{span, {min0, max0}, "Interval"}, minT, maxT, 5 60, 
          ControlType -> IntervalSlider}]]

![demo][1]

  [1]: https://i.sstatic.net/WpS5H.png