To an experienced hand that has setup rear ends before, its pretty straight forward and simple but a little time consuming to do properly. For someone that hasn't done one before, and has to ask how hard or what tools(I mean NO offence either), I wouldn't recommend trying without a significant amount of research prior. Tolerances, specs, patterns are very crucial to prevent rear end failure. Its very easy to fry a diff, especially when you rockin +1000 ft/lb at the wheels towing/racing.
At the very least you'll need Sterling/Ford 10.5" specs/tolerances, a press, bearing pullers, case spreader (not required but extremely helpful to prevent shim damage and proper preload), 1/2" click torque wrench, small dial style torque wrench to read +0 inch/lbs, dial indicator w/ stand, caliper gauge, brass punch, long punches/race drivers, pry bar, handful of basic hand tools, loctite, marking compound, shim kit, crush sleeve, bearings... A couple of those you may not need as long as your pattern doesn't warrant pinion removal and reshimming. Most likely you won't need to remove the pinion.
Pinion depth, pinion bearing preload, backlash, gear contact pattern, carrier bearing preload, bolt torque must all be within spec. It's a trial and error process, typically it takes few trys to get everything right. It's nothing hard to learn, but is a process with little room for errors.
Also if you having any thoughts of regearing, now is the time. Save yourself a lot of time and money opening them up once.