The best way to ensure the correct torque on the strut nut is to correctly torque it when its all put back together on the ground, not loose in your hand using a 21mm strut socket. 44ft lb and a 7mm allen. (do double check those numbers though)
Anyway, once the car is back on the floor, pull the strut caps off from within the engine bay and you won't be messing around trying to hold everything together on a loose strut / spring. hold the allen using vice grips or whatever, use the 21mm strut nut and a torque wrench. So much easier than two fella's hugging a strut assembly and messing around with bits and sockets not meant for the job.