IDK if this helps or not, but on another bike, I removed the carbs many times. I used to open the throttle on the carb all the way, hold them with something, then use needle nose pliers to thread the end into the holder. Then I was able to release the throttle to thread the 2nd cable end.
It was so tricky, I'd thread the cables before I installed the carbs. IDK what it takes to remove the throttle bodies, but that might be less work.
Long needle nose pliers were my best friend.