How to replace a segment of the code due to the difference of the the hardware?

Hi,
I have been following the world of Arduino for a long time and finally decided to commit myself to an Arduino project. I want to make the 'Sous-vide controller powered by Arduino - The SousViduino!' by Adafruit. The project uses 'RGB LCD Shield Kit w/ 16x2 Character Display which uses I2C but here in my country I can only get hold of the 'LCD Keypad Shield for Arduino'. I wanted to know how and what to tweak in the code so that I can use 'LCD Keypad Shield for Arduino' in my project.

Thanks in advance.

Links?
Code?