A Jim Turpin DVD saved me a lot of grief.
He advocates dropping the pipe straight down by carefully lining it up and, the way I interpreted it, inletting the tail first, marking the slot second and staying straight vertically. It worked well when I tried it that way, and worked even better when I did it BEFORE doing the front pipes.
I judge the biggest pain is getting all pipes lined up with the entry hole so the rod fits snug but not too tight. When you are a hobbyist rather than a pro the way I am, nothing is easy so I gotta go slow all the time, summoning more patience than I have and backing off for some coffee or lunch a lot.
I also found that running my drill bit, sans drill, into the hole just past the inletting at the tail and gradually twisting it by hand seemed to help.