No its not that difficult. Here is what works for me, remove the tire lay the rim on its side,scince its cracked try to align the crack hold it in place with vise grips. With a straight egde( a piece of steel flat stock from the hardware) lay and
it over the hub make sure it hangs over each side of the rim. Measure the space between the straight edge and the lip of the rim.Write it down.probably put the crack at 12 o'clock take your measurements at 9 and 3 o'clock.
Becuase we are budget minded on this job getting the spokes out are going to be the hardest part.If you can affrod it go buy one of those thick stubby spoke wrenches.Loosen all the nipples and begin removing the spokes make a drawing of which spoke starts first after the valve stem.There will be different lenghts of spokes so include this in your drawing
Replace the spokes on your new wheel start with that index one at the valve core,slowly tighten them by criss crossing as they get snug check your measurement,final tightening should give you the same space at four points 12-6o'clock and 9-3 o'clock.Mount the rim without the tire on the bike,tape a pointer (pencil) to the fork or swing arm spin the rim for final trueing if needed,Tightening the spokes on one side or the other will pull the rim in that direction. SOAK THE NIPPLES FOR A COUPLE OF DAYS they can be very stuborn hope this helps