The CineStyle picture style provides you with a flat, desaturated image: providing the best dynamic range of any of the picture styles for Canon DSLRs. Technicolor provide you with a file that you can apparently import into your editing software to help you grade your footage. However, I never figured out how to use it and frankly, I don't think one needs to. I think your time would be better spent learning how to color grade rather than learning how to import an .mga file. You don't need the file to grade your footage. I think it is more of a preset kind of thing – used to return the flat, desaturated image into a contrasty, attractive one albeit with more detail in the shadows and highlights than if you'd used any of the inbuilt Canon picture styles. However, this is something you can do yourself, and if done right, you will achieve better results than any preset can give you.
Most editing programs will have a color correction filter. Some programs have better than others but most should satisfy your needs. However, I will recommend a good piece of free software called DaVinci Resolve Lite. Like I said, it's free, and it's awesome.
Sorry I couldn't give you any help with the .mga file.