Soldato
You need a truing stand as well really.
It can be done on the bike, but it's much more difficult that way.
Doesnt sound right to me either. It can work on some hubs though, my fulcrum 7s are laced radially on the non-drive side and 2cross on the drive side. Not measured them but i'd guess that makes the spoke lengths similar for each side?
Pretty sure thats not the case for 105 hubs though?
Seriously, I've got Kinlin ADHN rims on 105 5600 hubs laced x3. The difference between DS and NDS is <1mm and so you can use the same spokes. I'll see if I can dig out the Spokecalc calculations.