When you get to be a backup feeder driver, or if you are lucky to get into feeders permanantly,there is training. Here, you get trained by a sup who went through UPS's DTS school. DTS is basicly boot camp for feeder sups to train their hourly feeder driver candadates.
My training was 2 weeks long with a DTS trained feeder sup. It's pretty intense. One week was a "non productive" training week, which we were paid for 3 months after training. The last week was "productive" training. There were no loads to pull, so we pulled "MT's" (empty boxes) around.
All in all, not a bad deal for training when some "CDL" training schools charge up to $3,000 for CDL training.