The normal route to making text slides is by creating them in Photoshop or another similar program. Here’s a little workaround video to getting them in Lightroom directly. For a black background to the text slides, simply take a photo with your lens cap on. For other styles, you could use a photo of a solid colour or texture.
In the Video I use Job Identifier as the holder for the text in the Slides, but you can use anything that is not used by the images in the slideshow. Make sure the text box you use in the Slideshow setup matches whatever metadata you choose.
The video is in .m4v iPod Video format so Right Click the link to download it. I haven’t done a video for a while, so excuse any mistakes!