MacOS- change homepage and default search of browsers

This program is for Macintosh (basically it must work on all Mac OS X versions starting from the Leopard version). I need a program that changes URLs of: 1. Browser Start Page 2. Browser default search provider It should change these parameters for the following browsers: Opera, Safari, Chrome and Firefox. I should be able to specify both URLs in a separate text file that comes along with the program. You should provide me with complete source code for the program. Please specify in your bid message or private message what programming language will you be using (it is actually not so important, but I want to make sure that you've at least read this post prior to placing your bid). Great rating is guaranteed after you complete this project in accordacne with these requirements. Thank you!