The place to come to share your technical expertise, or just find out what the little springy thing is that's just pinged out of sight under the work-bench.
I don't think there's a specific spot. The best way is to pull the cables upwards because the cables at the pulley end are thinner than the adjuster ends. I usually tie a length of string to the bottom nipple. Then when you get the cable through I undo the string and that helps you retrace your steps when you thread the cable's back through. Hope this helps.
Bit of advice. Buy a good bed and a good pair of shoes, because if you aren't in one you'll be in the other.
The reason I couldn't get my cables past the swinging arm is that they were actually run between the engine and the horizontal frame member (not the swinging arm..).
I only realised this when I stripped the back end and took the swinging arm out, though they must have been run past the swinging arm at one point judging from the cable-diameter grooves worn in it.