1997 Ford Ranger power sterring line access

Hi I am trying to get the pulley off the power steering pump but the pulley disc is in the way and I cannot get the two bolts backed off all the way to get the pump off and access the line bolts in the steering rack.I've inserted the allen wrench to the round center bolt piece but the rest of the srepentine assembly turns when I torque down. How do I stop it from turning? And is there a belt tensioner on the ranger to help take the belt off. Please let me know. Would be awesome advice thanks.