I used a DB Systems Protractor and another little gizmo that I cannot remember where I got it. The other Gizmo is a mirror with two sets of squares and you align your cart by moving the mirror back and forth from one null point to the other. I found the DB Systems protractor to be difficult to understand, and not nearly as precise.
The Wallytractor does take some time to get your cartridge aligned perfectly, because the tolerances are so small. Your are literally trying to get the stylus in a groove that is just a small scrath on a piece of glass. Wally does send along a helpful magnifying glass, which is the only way to magnify everything to make sure you are getting the stylus in the groove.
Go here for his detailed instructions:
http://www.simplyblack.net/pdf/WallyTurntableSetupProcedures.pdfGo here and click on Wallys Vinyl Corner for all of the stuff he sells:
http://www.simplyblack.net/There really is no other method out there that is this exact. And each one is custom made for your arm/table combination. He even told me that my pivot to spindle distance was wrong and I needed to move the pivot point a specific distance from the spindle. There is just no way that I could have known that on my table. But he knew immediately when I sent him my measurements. I have a Nottingham Sapcedeck/Spacearm and anyone else out there with this table should talk to him. The armboard can rotate around and he mentioned that armboard placement is very inconsistent on this table. Anyway, Wally is awesome to talk to, full of knowledge and will get your table dialed-in like no other.