Oz has been the focus of several crossovers in comics over the years, but usually with Wonderland. However, Hand Of Doom Publications printed out an on-again/off-again series(s) titled Peter Pan And The Warlords Of Oz.
Created by Rob Hand, this comic dealt with Peter Pan and the last two remaining Lost Boys, along with Tinkerbell and Tick-Tock(the crocodile who ate Capt. Hook)heading from Neverland to Oz via boat, which is weird since its surrounded by desert. Once there, they rescue the Lion who has been left out to die by Nazis that have taken over Oz. Peter & Co. team up with Lion, and then later Tinman who all plan to stop the Nazis. For some reason, Scarecrow, Hungy Tiger, Nome King, and Tik-Tok(the mechanical one) are working for the Nazis, whether they're under a spell or not is unknown. Meanwhile, Peter and his colleagues ally themselves with Ozma and one of the Wicked Witches who has an axe to grind with the Nazis, and together they manage to stop an evil golem. The Lost Boys along with Tick-Tock decide to leave, but Peter stays behind with Tinkerbell to liberate Oz.
This franchise was followed by Issue #1 to "Volume 2", then two one-shots: Dead Head Water and Wonderland Purgatory. The series is currently out of print, and very hard to find. I've only read the first issue, but you can find a more detailed review of some of this and some of the other issues here. There was a crossover with another Hand Of Doom series, Hammer Of Thor, where the Wicked Witch is sent from Midgard to Oz by Jesus(no kidding!).