Sure it can be done at home. I used to do it with a digital level, measuring tape and lines on the garage floor - parallell with the vehicle and 20 degrees out both ways at both wheels to get the caster. You will have to do the math afterwards to find/read the caster. Two pieces of sheet metal with grease between makes a good working turnplate. Might be a little messy. I finally got a used 20 years old rack for about 300 dollars. It was interesting to see how close my old school alignments was when I checked them with the rack. Do a search on here and you will find more info.