The ML-L3 allows for a single shutter depression, so you can't use it for continuous shooting (i.e. hold it down). You can press it 3 times in a row though and it will do your bracket series.
If you want to use a remote for continuous shooting then you'll need to use one that wires into the port on the camera's side. I have two, a Vello Shutter Boss, which is a nice wired remote that also works as a great intervalometer tool (far easier to understand and program than the in-camera method), and a Vello FreeWave RF remote, which sits on your hotshoe and wires in, but has an RF wireless remote that will trigger from up to 300 ft. away and does not require line of sight. The FreeWave has several modes: single press, continuous, bulb and timer.
If you don't have any potential need for the other functions then the press-press-press method with your current remote works fine (I used it for 18 months before I needed something else). Otherwise it's time for another remote.
Or (thinking as I type - a dangerous thing) set your camera in self-timer mode for 3 consecutive shots spaced at minimum time apart and the minimum delay (2 sec). This should automatically complete your bracket series, but it will mean you have to anticipate the 2 second delay before the first shot, so if you're waiting for a "moment" to happen, you could miss it.