Here’s my suggestion and the logic behind it after reading comments on several forums:
Everyone says FCP is really bad for dealing with text, especially scrolling text. You should use After Effects. I will agree, but I think I found a good way around having to buy After Effects just to do scrolling credits (because not everyone wants to buy or even bother learning After Effects).
Having worked on a few projects along side graphic artists, I often incorporated their work from After Affects into my interlaced Timeline. Often, their work was outputed with the “animation” compression, giving a nice clean, non-interlaced product. I thought that perhaps if I created a timeline in FCP with the animation compression and used Boris 3d Crawl, I could get the same kind of output. Turns out I did. That timeline, I just exported as a quicktime movie and then re-imported it to my project and placed it in my NTSC timeline.
Hopefully this will work for you