You mean the knuckle centering tool? I don't know of anyone locally that has one (but I'm sure it's possible). IIRC, it's about $120 from some SST place online. Somewhere I have a link to an article on how to build a tool that does the same job. I can dig it up if you're interested.
Are you putting on new knuckles? If not, just put the shims back where they came from and check the preload. It'll probably be perfect.
95% of the time, just splitting the shims equally between the top and bottom gets you close enough to work just fine and not leak. Of course, getting the knuckle bearing preload correct is vital, and there's really no magic trick to that, but it helps to have air tools for the 4th time you pull that bottom bearing cap...