Humanoids litterally can't outrun a pack of wolves, wolves are just faster. Wolves might well 'chase' them for a long while before attacking, to wear them down - common wolf behavior, AFAIK from the occassional nature-documentary - though.
If you want the Skill Challenge to be about escaping from the wolves, because the PCs are low enough level that they can't take them on, they'd have to reach a place of safety before the wolves exhaust them. Endurance would obviously be key. Athletics and Accrobatic could help, too - taking shortcuts by leaping streams or chasm or scampering accross a fallen tree or whatever. Nature should be a big help, since it would include understanding wolf behavior, how they track by scent, and how to lose them or scare them off - also, finding a place of relative safety, like a cave or settlement (History might help with that, too, revealing the location of an abandoned tower from an old border war or the like). Perception might help by being able to tell how far off they are.
So, as a start:
Primary Skills (moderate diff, can be rolled repeatedly)
Endurance (rolled exactly once per player, failures count - unless the party abandons the failing character)
Nature (rolled any number of times: can confuse tracks, find a path to a place of safety, discourage the wolf attack, find alternate prey that might distract the wolves, etc)
Helpful (can be used once each):
Accrobatics (can substitue for your own Endurance)
History (success counts, and reveals a place of safety)
Perception (success counts)
Athletics (can substitute for your or another's endurance)
Healing (can substitute for one /other/ character's Endurance check)
Intimidate (can only be used if the SC comes down to one last roll - at the end of the line, the party turns to fight and the wolves decide to look for easier prey).
possible outcomes:
Success: If the party used History or Nature to find a place of safety, the party reaches it before the Wolves attack, and can take an extended rest durring which the wolves leave in search of other prey. If Intimidate provided the last success, the party turns and presents a strong front as the wolves move to attack - and the wolves run off at the last moment. If the party abandoned anyone to avoid failure, that character is torn to pieces by the wolves, but the rest of the party gets away safely. Otherwise, the party is still fresh when the wolves attack (if perception was used successfully, the party is ready for the wolves, getting a surprise round), they do not need to defeat the wolves, only bloody a few of them, and the wolves flee (someone can use Nature to identify the alpha wolf, in which case, only that wolf need be bloodied to force the pack to flee).
Failure: The wolves attack when the party is on the edge of exhaustion - everyone who failed their endurance check is weakened & slowed (save ends both) at the start of the combat. If the party located a place of safety successfully, the wolves attack just before they reach safety - place the party at one edge of the map, if they move off the opposite edge, they are safe. If the party used Perception unsuccessfully, the wolves attack by surprise. If the party abandoned a character to avoid failure, that character re-joins the party just before the attack, with the wolves right behind him - and the abandoned character has lost a healing surge. If the party used Nature successfully, they identify the alpha, and can get the wolves to flee if they bloody the alpha and make a successful intimidate check against it. If all else fails, the pack flees if all the remaining wolves are bloodied. (unless they're just starving or rabid or demonic or something and will all fight to the death)
One last thought: Let the party decline the skill challenge and just fight the wolves if they want - make it a very tough encounter, though, and have the wolves (hungry, fresh, vicious and confident) fight to death regardless.