Best way to interpolate orientation?

This is related to my multiplayer project. I have a target XYZ rotation of an object. I have the current XYZ rotation of the object in-game. Similar to the way there is getVectTo(), and apply movement on that vector, i would like to be able to do that with the rotations of objects. Preferably if there is some function to do it rather than by hand

turn the orientation matrix into a quaternion and use slerp for the interpolation.