At our shop we use the torque wrench to put them in just like you described. One normally doesn't need to hold the tool in with a skewer or anything as the bb should go in easily by hand then the final "snugging" can be done with the wrench. Try using your left hand on the head of the torque wrench to push it into the bb and turning the wrench with your right hand. The torque is not all that much and by the way Barnetts manuals show that the torque range is from 260 in/lbs to 350 in/lbs not to 400.
-Ryan