ADK,
Coomonly used approaches to the Dixes include:
Elk Lake, with which you are familiar.
The Round Pond Dix trail from the North on Route 73. This is a nice approach, shorter in Winter because there's no road issue (they're about equal in Summer. Lot of camping ops. Great camping only 0.5 miles in at Round Pond, plus the Boquet Leanto is about 4 miles in. (You can also approach this area from the Ausable Club parking, via the trail that runs between Noonmark and Round, but it's more climbing that way.)
The "Hunter's Herd Path" leaves Route 73 at the bridge where the N Fork of the Boquet crosses the road. This is a great approach if you want to start with East Dix. There are numerous excellent camping areas on this approach. If you decide to go that way and need more details, there's a lot more info available.
Less commonly used approaches are West Mill Brook and Lindsey Brook, both of which feature culvert crossings of the Northway. West Mill is good if you want to start with East, South, or McComb. Lindsey is good if you want to start with East. Also great camping on those approaches, but there are fewer people, so you might be breaking more trail. More detail is available on those as well.
Walker Brook, which also features a Northway culvert, is not really practical for approaching the Dixes.
The other ways I've hooked into the Dix trail system is by bushwacking down from the Bear Den-Dial-Nippletop ridge. If you start at the Ausable Club, it's a pretty easy bushwack down Gravestone Brook to the Dix trail (although it would really be going out of your way for no reason). I've also bushwacked down from near the summit of Nippletop. It was downhill, but exceedingly thick, and would be a bad idea in the Winter.
Have fun!
TCD