how to change mac hard drive icons

You can copy/paste ICNS, jpg, jpg2000, tiff, gif, PNG and PICT data as a custom icon. 

• Open an image file in Preview (for example), press Command-A, Command-C  

• Then select the file/folder/hard drive you want to set the custom icon on,

• select File->Get Info.

• Click on the icon in the upper left corner of the Info Window (it should show a little hallow around it),

• press Command-V.

Poof... your done.