Here is the update.
We received from the pharmacy pre-loaded syringes with the B-complex mixture, a vial of 2% lidocaine, and some extra syringes. The procedure is to remove the needle from one of the B-complex syringes, draw the plunger back far enough to make room for 0.25ml of lidocaine, draw 0.25ml lidocaine from the lidocaine vial with one of the extra syringes, put this lidocaine into the B-complex syringe, put the needle back on the B-complex syringe and do a standard IM injection.
So basically, when you inject, the 0.25ml lidocaine is the first thing to go into the tissue.
Not sure why she couldn't just draw the lidocaine with the B-complex syringe directly. The nurse giving the training wasn't the kind you could ask questions like that, the answer would be "because that's the way we do it around here".
Interestingly my wife said the injection was painless and she did not have the bruised feeling in her leg that I get when I inject test. cyp. IM in my leg. I wonder if the lidocaine has anything to do with that.