Yup. Or use the wings of flying wondrous item or somesuch.Geoff Watson said:The rider is a spellcaster who casts fly or a similar spell on the wyvern.
The reason that a wyvern skeleton would be better for this than a regular non-winged skeleton is because skeletons cannot be trained, but retain much of the proficiencies they had before dying. Therefore, a wyvern skeleton should be capable of using a fly spell effectively. A regular skeletal warhorse would not.