Just an edit suggestion...."Chuseyo" or "Juseyo" means "give me please", not just "please". The "seyo" part is the actual "please" and can be added to any verb to make it more polite ie: go = kayo, so "please go" = Kaseyo. :)
Actually "please" is Jaebal (제발) but you are right that say-yo part is a polite ending.