M.S.
agree with other posters.. keep her fiber/veg & fruit consumption up (keep things moving and soft). lots of fluids, etc. don't push too hard, she'll give up the diapers eventually.
a couple ideas.. one, always, always dump the poop (from the diaper) in to the toilet and say "bye bye" to the poop. I used to sing a little song about how poop goes in the potty and we flush it down.. and tell her that someday she can poop in the potty without using a diaper.
two, I know you said bribes don't work, but you might try different things, like a potty chart on the door... with spaces for pee and poop. with my daughter it was a sticker for number 1 and a temporary tattoo for number 2... don't know why, but she loves the tattoos. my sister used m&m's.. one for pee and three for poop. you never know what works.