This does the math. Just add a Text or Rich Text module, "Edit text manually" and insert this.
You will have to also tap "Override widget Locality" add a location, enter any city and manually set the timezone to UTC. This is because it Swatch Internet Time doesn't have time zones but can be calculated from Biel Meantime (BMT). @0 is midnight in Biel, where Swatch has it's headquarters.
You can also download this as a template: Swatch Internet Time.zw