The way I was thinking was like this.
1. End of Chaos players movement phase: Roll a d6, on a score of 1 the ship does not make the transition from the warp and remains in reserve. On a 2+ the ship may be deployed anywhere within 20cm of any capitol ship, facing in a direction of the Chaos players choosing. As it is placed at the End of the movement phase It may not take any special orders or move in any way.
2. Subsequent Chaos players movement phases: The ship may move as normal (we can add that it may not take special orders if needed). At the End of any subsequent Chaos players movement phase a spectral Daemonship may finalize the transition and become solid. Upon appearing a leadership test must be attempted, if the ship fails the leadership test all weapons firepowers and strengths will be halved until the next turn, if the ship passes its weapons will all be at full strength. From this point forward the Daemonship functions exactly as any other ship.
3. Subsequent Chaos players movement phases: The Daemonship may during any subsequent Chaos players movement phases disengage. There is no test for this, it is simply removed from play and placed back into reserve.
4. Subsequent Chaos players movement phases: The process starts over, refer to step 1.
Ok so after thinking on this a bit there should be some penalty for disengaging to keep people from popping out, slugging it out till they suffer a couple hits, then disengaging gaining hits back and starting the process over.