Have a go has it right on,
2 guys on my old team are 5'6" and both hit the D2 national provisional mark. What is important to do as stated above is to go to the track and practice jumping over sprint hurdles first, and then practice over the steeple barriers, and as you should know, the guys height is 36 inches (~ 30 for girls).
It is very, very important that you practice before racing. Those steeple barriers, and especially the water pit, look much bigger during a race. I have seen quite the look of terror when approaching a water pit having not practiced it.
For note, your first steeple race is not going to be your best one. Try it out and see how you feel. You may not like it but chances are you will go faster the 2nd time. once you have it as a specialty, for reference, it is "assumed" that your 3k steeple time should roughly equate to your 3200m time.
Good luck.