Help with changing phpdev4.2.3 to work with php5

hello there,
i am currently using codeigniter which works perfectly with php4. I have
phpdev4.2.3 installed but now i need to work with kohana framework which
is only compatible with php5. i have the zipped folder of php5 but not installed yet
Can anyone please help me with a detailed explanantion on the necessary configurations
i need to make so that my phpdev works with my php5. Please