"lets say hypothetically someone gets the minimum requirements and then gets a job working as a package handler or seasonal driver help. Would that person be able to apply for the position from the inside"

That sounds like the Fedex deal. I've heard they guarantee an interview if you work for them for a period of time (do a search, it's been discussed before). The problem is, you have to meet the quals and be current. Hard to quit the RJ Capt job, throw boxes for a year, and still keep the RJ currency. Anyhow, I've heard that guys have got in there that way. It's only an interview, too, not a promised job, so I see it as a big sacrifice that has a good chance to not pay off. As fas as UPS doing something similar? I've never head of it.

I do agree with some of the above posts, that boxhead HR types would eat up previous box throwing at the interview. I just disagree that it would somehow be a shortcut to the interview in the first place which I think the OP, as a 145 F/O, is looking for, based on the first post in the thread.