I think the DVP-250 firmware will also work with the K2. Not 100% sure though!
The firmware does mention the K2 in it`s header, so might be worh looking at.
Also I tried the 705 firmware in a 250 which enabled Karoke on it! So maybe that might work also?!
Try http://www.theironduke.plus.com/HitachiSyndicate/ for the files..
RikD.