Hi there,
I’ve just released a pack of plugins which might be very useful for your job. It creates slideshows from a folder of images on the timeline in FCP or motion.
You can download the free 14 day demo from here:
https://www.coremelt.com
There is no watermark or any other restriction for the first 14 days, so you can probably do the job with this.
I would recommend to rescale your images to just above your project resolution eg 800×600 72dpi. The plugin reads in the files outside of FCP so it can use the full file resolution but if you don’t need a super zoom then this will be fine.
If interlace flicker is a problem, render progressive as others have mentioned, but it depends on the speed of your move on the images, you may not need to do this.
Hope you find these useful, the plugins are $99US to buy the pack with ten different animation styles of slideshows.