Is it possible to use a skeleton as a vessel for a possession-based spirit?

yes.

Thank you; now, for the corollary that I probably should have placed within the OP: What would a good set of base stats be for a skeletal vessel? I know that corpses can be used as vessels, but those are subject to decay, and have no minimum at which they cease being "corpses" and become "skeletons". They just decay until they reach 0, from what I can tell.

On page 86 of Street Magic, it says Zombie Vessels reduce to a minimum of 1. You could go with that. Then the Physical stats would be 1 + F, and the mental stats F.

A GM who is a stickler for physics might wonder how the various bones of the skeleton are held together, but tendons can last a long time after other soft flesh has decayed.

Or you could use pins and wires.

Or you could . . you know . . explain by saying the following:
A WIZARD DID IT!
Which is true. And it's a Spirit inhabiting it. IT'S MAGIC! Logic/Physics can go kiss my skeletal ass <.<

you are my new favorite person...ima facebook stalk you now
http://www.penny-arcade.com/comic/2009/11/2/

I hate it when a GM has to nitpick to explain every little detail and "HAS" to stick to the rules in order to make his players happy, sure in some instances the world need to revolve around an understood principle of rules that the characters understand...
but then...
other times...
you have to completely and utterly just rip their sanity out of their skull and eat it with a spork carved out of the fecal matter left behind from the guinea pig that ate their kidneys.

Usually, i am a big supporter of the Gm sticking to the rules and logic and the such . . . Only in the Case of Magic and inside the Matrix i am of other opinion . . .
Also, i am not on facebok so nyyaa! ^^
But stuff like this really irks me.
As long as it is coherent in the universe of shadowrun, i don't care about what our world has to say about that ^^

i think its a conflict between the setting and the concept of games.

that is, you expect magic to be random, powered mostly by the will of the wielder.

at the same time, you expect a game to be consistent in its rules. You expect the GM to be consistent and impartial, just like a judge handling issues of law.

this is probably why no magic system will be really "magical"...

Shadowrun: The Game where Magic has a set of hard more or less logical rules and Computers/Networking is basically handwaved as a new kind of magic.

You might be able to get away with using the "Animate" spell. A skeleton is inanimate.

Game designers could be required to have consultants on hand during development to ensure that their system conforms to natural laws and modern SOP, but Science has always been treated as a hand-waived magicky element.
That way you can do science to it.