I have the spacer tool for my set and used it for my coarse alignment. It will spot if you have a pin that is really out of position, but with tolerances and all the possibilities that the pins could take, it isn't perfect.
Because it is only about 1/8" thick and the pins are about 1 1/4" long, it will only spot issues within it's thickness range. You can still have the pins get into a bind when you put the wheels on. It then takes rotating the wheel on the pattern to see where it fits best.
You can get the wheels to line up without the tool but it can be a real bear to get it done. Lots of on and off trying to troubleshoot. The tool is very quick to spot issues. If the spacer starts to bind up, there is no way the wheel would ever go on.
You can get the tool from Trigo:
Alignment Tool $35 plus shipping
I originally tried to mount my wheels without it. Consumed more than the $35 in beer trying to get it done on the first wheel and had three left to go.
Paul