Present subjects with a long-form writing task about anything - most likely, you'd be best-off supplying a topic that's difficult to write about (self-analysis, distant dates, self-assumed tardiness, etc) and not fun to think about. Don't set a time limit or a word limit, and stress that it's important they answer fully, completely, and honestly. If you want best results, you should aim to have a secondary control question that's meant to be easy to reply to, or relaxing, or ultimately nice to think about. Maybe pick "The best time of your life" vs. "The absolute worst time of your life".
Then provide them with a procrastinatory task. If you have access to the room they'd be doing this in, provide something hard to notice on first go, but actively distracting - for example, a Spanish soap opera on mute. Up to you on behavioral protocol here - you could watch it while you wait (and risk influencing the subject to watch it too), not appear to notice it, etc. Your goal at this stage is to be able to measure the time spent not working on the task - you might want to make notes of when they look away, create a program that records exactly how much time is spent not inputting data, etc.
You can also choose to make the testing separate and instead only give a single type of test (easy/hard) to a single person, and that person's procrastination responses are recorded. Etc.
The important thing to remember is that you don't need to invoke the purest sense of boredom or negative emotion to make a subject procrastinate; you only need to gently invoke procrastinatory emotions, and then provide a suitable distraction.
