Matthew. I haven't heard of the Livery Installer you mention. I don't suppose it would know which type of aircraft it's dealing with.
In my experience it usually takes longer to figure out how to use this type of utility than to do it manually. At least if you edit the files yourself you know where to look if anything goes wrong. It's really much easier that it might look once you understand the basic principle. Please read my little walkthrough carefully. I originally wrote it for one of the regulars here & he persuaded me to post it for everyone's benefit.
If you still can't figure it out give me an example & I'll do my best to walk you through it.