Same usage as usual. The keyboard patch is now very easy to create (see the spoiler).
Edit: Even though Kobo has now its own large scale mode, I will probably continue to provide bad eyes patches. One reason is that they contain also other things that are useful to me. Also with respect to readability, I still like some solutions of the bad eyes patch better than the one provided with the software. Cf. the image (from left to right, original - bad eyes - original large scale mode). The image is taken from FW 4.4.9960, but the results should be the same.