The only way to do it 100% is with a housing jig… Although I have seen people do it the way your mentioning…Another good DIY way is with round tubing that slides through the housing…It has to be exactly the diameter of the axle opening (for tapered housings) with the tube through the housing you can cut and slide pieces around without messing with the alignment too bad… (not sure if i explained that so you can visualize it)
There are also other things to take into account…For cars that are going to be high HP drag style… some people set the axle housings pre loaded for torque… Its twisted and only truely aligned when the foot is down on the gas…