I cannot find the guide to get started with using HarfBuzz in my own app.
I looked here:
http://freedesktop.org/wiki/Software/HarfBuzz/
This seems to be the official page of HarfBuzz.
I looked over Download, Building and Development sections. But I must be overlooking something.
I was facing the same issue and was looking for the instructions. Finally I found at below link. It includes Android sample app with build instructions and all. Enjoy : Indic-text-renderer