In reply to HenryJM: getting up and down the valley on the main road (Highway 9) is fairly straightforward, as long as you're not overly enthusiastic with the accelerator or brakes! No problems at all getting all the way from Rysstad to Hovden, and didn't really feel that our non-4x4 hire cars were struggling.
Last year's conditions were a bit poor over the period we were out there (new year - hopefully Feb will be better for you) so we spent quite a lot of our time further afield - climbs were better formed out on the Dalen road (Highway 45) so we drove that quite a bit; it was more exciting driving than the main valley road but, again, fine as long as you're sensible. Once or twice we felt it wise to dig out the snow from a layby before parking up.
In fact the only problem we had was getting back late one night to find the road up to the hytte park at Brokke was in a bad state and we managed to slightly damage the underside of the hire car, which was an expensive mistake. The road seems to be fairly regularly ploughed, so I think we were just unlucky.
The Brokke hyttes are lovely, by the way - thoroughly recommend them. Much more info, including recent road conditions reports, at the website:
http://www.climb-setesdal.com/
Cheers
Jamie