This short TR from last weekend describes the difficulty of driving to Winfield. When the author reports parking "one mile from the trailhead", they likely parked a little beyond Rockdale. I suppose,though, they could be referring to one mile from the 4WD TH which would mean they made a mile past Winfield. Maybe a PM to mountaindude will clarify.
http://www.14ers.com/php14ers/tripreport.php?trip=7465&cpgm=tripmain&ski=IncludeEither way, even with melting from this week, I don't think you will be able to drive any of the 4WD road. You'll be starting at Rockdale.
I would plan to snowshoe or ski to the 4WD TH. Outside times of extreme avy danger, there are ridge routes from here that you can use to avoid avalanches if you pick carefully. Lou Dawson's book recommends this side of the mountain for winter or winterlike conditions.
Personally, my first winter attempt on 12/24/06 was foiled by wearing myself out on the circuitous route needed to avoid avy danger on the Vicksburg (east) side. I came back in January and succeeded on the Clohesy Lake side. This is the first TR I wrote for 14ers.com; it is not as detailed as some later reports.
http://www.14ers.com/php14ers/tripreport.php?trip=2842&parmuser=sgladbach&cpgm=tripmain&ski=IncludeSteve