In reply to Chesher cat:
Not at New Year. I think the earliest I've done it has been March. It's pretty staightforward - ski down the Ewigschneefeld(?) for a little way till you can skin up right and on to the ridge. Can't remember if the 'ski summit' is the true summit or not. The best descent is down the S side but this would leave you almost down at Konkordia with a long skin back up to Jungfraujoch. Maybe you can cut rightwards? Probably best would be to reverse your ascent route. No idea at all what conditions you could expect in January though. Maybe contact the G'wald guides or ask someone like Graham Frost who might have a better idea:
http://www.ukclimbing.com/forums/profile.php?id=72625
