Its physically impossible in Garry's Mod, unless your using HE and have some good scripting skills.

It is possible but slightly difficult to do in practice. To accomplish this you will need to parent your animating npc or ragdoll to another object that has physics (I use superparentmulti tool). Then any move that happens to the parent object will affect the animating npc or ragdoll as if it was welded.

This makes it possible to move the animating npc by either thrusters, ropes, etc. This will also make the npc a physicsless object in that nothing will interact with it, not even the world boundaries.

You can also change the animation of the npc without affecting the parent.

I've found a better method, using superparentmulti as above and using Henry's animation tool to control the parent object and using wiremod expression2 for triggering of animations you can create sequences of movements akin to a cutscene.

Or you could use Stop motion helper. maybe.