Hi Snap and welcome to the forums.
I am guessing that you are doing the classic Black Officer:
http://databank.501st.com/databank/Costu...icer_black
I would strongly suggest that you head on over to the detachment
http://www.imperialofficer.com/forum/ to do your research.
A lot of our officers do use the cosplaysky officer uniform. One of our members actually talked to them and they have altered the costume to get it to be more accurate. There are local makers of the hat and belt which are more accurate than you can get from cosplaysky.
Have a read through this thread for the approval process.
http://www.501st.com.au/forum/showthread.php?tid=6720
Also can't hurt to read this one too:
http://www.501st.com.au/forum/showthread.php?tid=6719
Have fun, any questions just ask away.