Any particular reason you don't want to use cubase for scoring. Supports video and timecode, you must already be comfortable with it, seems like a good fit. Most composers I work with use Cubase, Sonar or Logic. Just depends on preference, so I think you are set. Get the video with timecode burn-in (imposed on the picture) so you can double check it against cubase's timecode and start composing.
Maybe you should call Hans Zimmer, Steve Jablonsky, Harry Gregson Williams, and a few hundred other composers who score films with Cubase and tell them it sucks at the job. I'm sure they'd like to know such great advice.