Both the hanging corpses and being crucified are implemented as hacks.
For the hanging corpse, you have to add an invisible platform in the air, and then place the character on this platform. The hanged death state will place the head above this platform and the rest of the body below it.
The crucified characters (at least the gheists) are implemented using a custom sitting animation. They are scripted to "use" their crucifixes, which makes them "sit" on it, and the sitting is shown as them hanging from the crosses.