I use a similar spray. Just garlic and pepper though. I know stuff like liquid fence has egg in it how exactly do you incorporate egg into the mix? My major problems are with chipmunks or some kind of rodents too.
I mix the garlic powder and cayenne in water then strain the solids out with a coffee filter. I've been looking for a way to get better solubility and make it last longer and someone suggested I try oil rather than water. I'm not sure about that though, I feel like they may actually be attracted to oil.