easiest way is to find a a spot with an overhanging branch on a deer trail, scrape up a section with your boot, and pee in it.
if you're worried about the human pee thing (which I'm absolutely not), straight grocery store ammonia works. I usually carry a 20oz soda bottle full of ammonia when I'm starting some scrapes.
or you could go the expensive route and buy something like 'scrape juice'....I've even see somewhere where they sold fake scrape dirt! all gimmicks to separate a hunter from his money IMHO.
I have heard of guys scraping up the dirt from a real scrape and 'transplanting it' to a more suitable hunting location. may work...never tried it.