It can be really easy to use a pump for intermittent feeds. There are two basic ways to do it. The first involves programming just the dose (amount) to be delivered and the rate you want it delivered it. When the feed is done, the pump will beep and can be shut off.
If your child gets more frequent intermittent feedings, you might want to use the Intermittent or Interval Mode, which is available on most pumps. In this case, you set the dose and the rate, but you also select the interval you want the feeds to be given. For example, if you want to give a feeding every 2 hours, you would set the interval to 2 hours. See this tutorial on how to do set the Interval setting using the Infinity pump.
The two most common pumps have interactive tutorials to let you practice how to program the pump. See the Virtual Infinity Pump or the Kangaroo Interactive Tutorial for more assistance.