Runway landing with a front skid instead of wheel - how does steering happen? (Dreamchaser)
Like many aircraft that dont have a steerable nose wheel they most likely use differential braking. Here is a pretty interesting paper that covers some of the testing they did on the airframe. Steering is not really a large concern for the Dream Chaser (or the space shuttle for that matter) as it has no power to maneuver on the ground anyway. Generally speaking it will be towed off the runway.  

According to this source SNC notes similar reasoning to the X-15, simplicity as well as concerns around tires in a space environment (which is interesting seeing as the space shuttle had them). 


  Speaking of the rationale for opting to use a skid strip, SNC noted it
  is a simple, light, safe option. They also added that there had been
  some issues with the analysis of the performance of tires in the space
  environment and this eliminates one of the tires – with the other two
  tires easier to control than the nose wheel if there’s a problem with
  one of them.
  
  SNC noted they do not expect any crosswind limitations from the skid.


Although here is a fairly interesting NASA press release on testing the "nose gear" for the Dream Chase implying there may have at one point been gear there.