This is a lisp routine that swaps object colors. After you load the lisp using Appload command enter colorswap command. You will see color dialog to pick first color. After you select color to be changed you will get another color dialog to pick second one.
You can download the color swap lisp routine here:
Lisp also contains a sample lisp routine to automate your color swapping jobs. If you are doing color swap regularly you may want to modify this routine to fit your needs.
Hope you like it.