Don;
If possible, use the old wire as a pulling wire...but it sounds like you may not have this option anymore...
Because the hole in the endplate of the steering box is smaller than the tube, pushing it
down the tube is quite difficult...pushing it
up is the way to go...see also:
http://sw-em.com/service%20notes.htm#Steering
You
may need to loosen coupling in steering column to get past it...you can thread in a thin wire as a pulling wire, but it is important to finally use 600V rated (double thickness) insulated wire for this application because it is subject to vibration AND motion.
Cheers