No real standard way to do it. You just have to use what you have avaliable.
For starters, you need to buy/comeup with/make an auger.
Then you need a rear end. You will cut one axle tube off and remove the axle. Then you have to weld the spider gears together to force the axle that is left to be the one that turns. The PTO will drive the pinion, and the axle that is left needs to be cut down, and adapted to the auger.
This will also require a bastard size PTO shaft joint most likely.
And it is best to find a rear axle that has inboard seals and not outboard wet bearings. Otherwise, it wont hold lube in the diff.
Honestly, this day in time, it would probabally be cheaper in the long run to just spend $500 and buy one. Unless you happen to have a rear end, auger, AND pto that will already work. But to just buy a PTO shaft and auger you would probabally already be close to new PHD price.