bmw e34 525 diff preload?? how to do it?

[slidea5]

i've just had to do replace my pinion bearings in my lsd after they failed due to me not taking care when fitting the flange a while ago. now the time has come to rebuild and replace bearings. the job is done and the diff is back together apart from the preloading bussiness. i need to torque the pinion nut up to 186nm [137lbft] but dont know how to do it without everything turning. is there a way i can lock the diff up???? has anyone had to do this ???? help much apreciated... thanks