I personally know 2 guys that were internal hires at FedEx, including one of my 14 Jan classmates and a crash pad roomie.
One guy threw boxes for several years at night, and another was an avionics mechanic.
Warning: the job isn't yours automatically if you are hired interviewed from within. Conversely, it seems to me to be a VERY tough process. Most internals don't get picked up on their first try...average seems to be second hack. I have NO idea why this is, and its all anecdotal, but maybe some others in the know can share their experience.
Bottom line...I wouldn't pass up a flying job to sling boxes hoping for the best. On the other hand, if you can work part time for FDX, that might just be your ticket to an interview.
Albie