Preload is the measurement of how much torque it takes to turn over the pinion gear alone once the crush sleeve is crushed, not the torque of how tight the nut is. Usually you don't want to get it tighter than 25
INCH lbs. with new pinion bearings. I use a inch lb torque wrench that has a needle on it to measure preload, it would be a PITA to use a click type torque wrench to do it. Once you start getting a preload reading on the torque wrench it doesn't take much to reach 25 inch lbs, you would be safe if you can get it between 18 and 25 though.
The crush sleeve will take allot of effort to crush by hand, I use an impact gun but I wouldn't recommend it unless you have done ALLOT of rear gear swaps.
Here's some more info you can look at for rear gear swaps, you should find it useful <img src="gr_stretch.gif" border="0"> :
http://sethirdgen.org/10bolt2.htm