References along these lines may help:-

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3695356/

I think you need to provide more detail on which aspects of HD you are trying to model and which parameters you wish to investigate. The above reference outlines how to transiently express normal and diseased huntingdin, and how to quantify aggregates in several ways. However other objectives may benefit from quite different approaches. SH-SY5Y cells are not the easiest to work with, so I would allow plenty of time to gain consistent results, (transfection efficiency etc). Good luck.