Katy it just a way Ive been doing it, dont know if you could as you have a bigger setting, involves no clothes at the bottom for a few days.
But if you can try this
POTTY TRAINING
Day 1 - 3 no clothes, ask if they want the potty, at least every 1/2 hour. Expect lots of accidents.
Day 4-7 Providing child is now making it to the potty, pants on, still reminding, first couple of days will result in wet pants, but by day 7, usually making it to the potty.
Day 7 onwards trousers on as well, still asking often, take potty EVERYWHERE with you.
If this doesn't work, would say the child isn't ready. Have done it with children from 20 months - 4 years, they are ready when they are ready, boys in general are later than girls, but saying that just had a boy dry at 22 months and a girl not till almost 4. !