Google can be your friend - http://www.autotoolworld.com/Ajax-Tools-690-Cotter-Pin-Remover_p_123040.html
Now, just "how" one uses it...
Mark
Well, they do get a little bigger than what we find on passenger vehicles. Think mining equipment, power generation, other heavy industry. I believe they make the regular split cotter pin up to about 3/4 x 8" or so. I have seen them 1/2 x 4", and needle nosed pliers would be no help there.