I've put in my own highlights for years. It's not hard at all and saves a bundle. You just have to be careful not to do too grab too many strands of hair per highlight. I get dh to help with the back of my head where I can't reach.
I'm not sure what they meant by using Excellence to Go. That's an all-over color. Loreal sells a kit, Couleur Experte, that's got the all over color and highlighting. It's a two step process. There are other types and brands out there that are just highlights that you use after you've used the all over kind of your choice. I've tried most of them. I don't like the kind with the caps, but that's just me.