Brake Duct Screens

This is probably a stupid question, but how do you install the screens for the front brake ducts. I have already installed the fog light screens and the side cove vent screens, but the brake ducts screens have no instructions. I order them from Eckler's and their catalog simply says pressure fit.
What do I need to remove to get this in place. I know they do not simply go in from the front of the ducts, so something need to be removed. Any help would be appricated.

I was up early browsing and found this

http://www.spdkilz.com/techtipfrontscreen.html

Hope it helps

Thanks for the reply, but I did get them in last night. Actully a lot easier then the method shown. I simply covered the painted area with blue painters tape to protect it. I then put the screens in from the front. I inserted then in on an angle with needle nose pliers. once they are back beyond the painted area, I pulled them forward and they will slip right into the ducts. there is a ridge there that they fit into and once they were pulled back forward they were set. It only took a few minutes to install them.
But again thanks for taking the time and sending this link.