I haven't read the book or anything but in general terms I think you just pick a breed that has the trait you're looking for and do a first generation cross. Then from there you breed the crosses together and keep the offspring that have the traits you want. Depending on the mode of inheritance you then breed back to your original breed over multiple generations to get back to the original breed type, while only keeping those offspring that have inherited the desired trait and culling those that didn't or have obvious traits from the crossed breed. I would think for silver laced orps you would probably use silver laced Wyandottes, at least then you don't have things like muffs/beards/crests/feathered legs that you have to breed back out of your project birds.
How did u know I was talkin about orps?