Multiple facts working against you:
(1) UPS prohibits management from returning to hourly status.
(2) Your separation was involuntary.
(3) Your separation was recent.
It's EXTREMELY unlikely UPS will ever rehire you. You should've challenged your termination (p/t sup are entitled to arbitration); at the very least, you could've bargained for your separation to be recorded as voluntary.
Not that I'd understand why'd you want to return to UPS, anyway; you were probably making at least $25,000 and would be lucky to top $10,000 as a new hire. Learn a lesson and move on. If you're still determined to work for UPS, my suggestion would be to apply for a seasonal position at an alternate center (or alternate shift) - they may be more lenient (heck, you're trained, right?) and the worst they'll do is tell you no.