Changing Code to toggle LED ON or OFF With Unity 3D

I had mentioned in my first ever post here that I had been following the tutorial one here: http://r3dstar.co.uk/?p=211

I did get it to work fine but what I need is to have the LED's able to toggle on or off but because I am new to Arduino and how it interacts with Unity 3D I am not sure what to change in the code to do this.?

I have put up a video on my blog showing my progress with my project, as you can see the previous LED turns off when the other button is pressed but I need them to stay on until turned off by clicking the button again. Here is a link to my video on my blog:

http://myknightrider2000.blogspot.ca/2015/09/dash-software-to-arduino-experiment-02.html

If anyone is familiar with the Unity C# code in the tutorial and can help that would be great :)