Forsaken Bounty doesn't even give a hint, although the resume on the back of the RT core rulebook promises there are ways to do so. That's not good, sadly...

Here's what FFG said about designing starships in a previous news entry/designer diary:

http://www.fantasyflightgames.com/edge_news.asp?eidn=457

It's also known that there will be a tweaked psy system - guess how much the demo adventure reveals about that.

  The problem with starships in the WH 40K universe is that they are MASSIVE! According to the website Jeff Russell’s Starship Dimensions, (http://www.merzo.net ,) even the humble little Cobra is tens of times larger than the mighty Galactica. The Starship Enterprise, NCC-1701, (no bloody A, B, C, or D,) could be carried as a shuttle craft. The only vessel of comparable size is the Imperial Star Destroyer of Star Wars. It could be suggested that on the larger vessels, some of the crew would not be aware that were on a ship. There is no suggestion that an adventure class vessel, (examples, Millennium Falcon, (Star Wars,) Serenity, (Firefly,) or White Star, (B-5,)), would be able to enter the warp.
  On the other hand, there are some advantages to having such massive ships. Some of the literature states that these vessels are millennium old, and have been repaired, and refurbished over, and over. In the process, sections of the ship have been cut off for centuries. In the long periods between destinations, the ship could become the adventure.