Is there ANY way to activate a planeswalker ability at instant speed?

Question

With the vast richness of magic rules on all the cards and the comp rules, is there any way at all to activate a planeswalker ability at instant speed?

Typically, per the rules, you can only activate them once per turn as a sorcery, but are there any ways around this? Since the "golden rule" of magic is that when a card and the comp rules conflict, the card text wind, I figured there might, possibly, be a way around the restriction.

Relevant rule we are trying to dodge:

606.3. A player may activate a loyalty ability of a permanent he or she controls any time he or she has priority and the stack is empty during a main phase of his or her turn, but only if no player has previously activated a loyalty ability of that permanent that turn.

Answer 1

Since the other answers have been written, a card has been released that explicitly allows activating loyalty abilities any time you could play an instant: Teferi, Temporal Archmage from Commander 2014.

He's a planeswalker with a relevant ultimate:

−10: You get an emblem with "You may activate loyalty abilities of planeswalkers you control on any player's turn any time you could cast an instant."

So if you manage to get him to 10 loyalty and activate this ability, you will be able to play loyalty abilities of planeswalkers at instant speed. It's not an exciting combo or abuse of the rules, but it can still be a lot of fun in a slow multiplayer game—exactly what the whole Commander 2014 set is all about!

As for activating loyalty abilities multiple times in a turn, that is possible with The Chain Veil. A card first printed in 2015, long after the question was originally asked.

Answer 2

There used to be a long shot that could make this happen:

• You start by playing the Mycosynth Lattice which turns all your permanents into artifacts, including planeswalkers.

• Then you play March Of the Machines, turning your planeswalker into an artifact creature with power and toughness equal to its casting cost.

• Then you use the ability of an Experiment Kraj to put a +1/+1 counter on the planeswalker artifact creature.

• Now since the planeswalker artifact creature has a +1/+1 counter on it, the Experiment Kraj can use all of the activated abilities of the planeswalker without any of the restrictions of a planeswalker.

Sadly since the time of that post they have extensively written into the rules that there is no way to use a loyalty ability of a permanent in any way other than a sorcery and it can only be used once per turn.

209.2. An activated ability with a loyalty symbol in its cost is a loyalty ability. Loyalty abilities follow special rules: A player may activate a loyalty ability of a permanent he or she controls any time he or she has priority and the stack is empty during a main phase of his or her turn, but only if none of that permanent's loyalty abilities have been activated that turn. See rule 606, "Loyalty Abilities."

606.3. A player may activate a loyalty ability of a permanent he or she controls any time he or she has priority and the stack is empty during a main phase of his or her turn, but only if no player has previously activated a loyalty ability of that permanent that turn.

To date with the exception of copying an activated ability, there is no way to use a loyalty ability more than once and you can never use them at a time other than when you could cast a sorcery, because they have restricted the use of the loyalty ability itself, not just the way a planeswalker specifically uses them.