I have used the program CandyBar to manipulate icons systemwide. It works for individual applications to. It has a trial period of 30 days, but it only counts the days that you use it. I have had my computer for 2 years and it has still not expired. I would recommend checking it out.

http://candybar.en.softonic.com/mac

I have used the program CandyBar to manipulate icons systemwide. It works for individual applications to. It has a trial period of 30 days, but it only counts the days that you use it. I have had my computer for 2 years and it has still not expired. I would recommend checking it out.

CandyBar Website