Is it possible to customize the homepage to have the slideshow on the right and categories or galleries on the left of the slideshow? Here's my site as an example.
You'll want to stretch your Homepage, and float the containers for the slideshow and categories left and right. Assuming that you want each to take up 50% of the available screen real estate, you can set the width to 50% on each.
Add this to your Advanced Customizer > CSS section: