I applied via application form online and passed it into store at the customer service desk on a Friday, I was called on the Sunday to go in on the Monday for a Star Search, which is what they call their interview process. It turned out to be a group thing, which I suspected as I'd read online about them.
First we had to do an ice breaker, the usual "talk to the person next to you and find out about them and an interesting fact and present them to the group" thing. Easy really just talk and ask questions!
Next we were split into half, there were 10 of us so 5 on each side and they gave us topics to discuss. Our topics were "The internet should be banned" one half for banning it one half against, and "customer service is the most important reason customers come to the store" same things, one agrees one disagrees. They also had a topic of "footballers are paid too much" but we didn't discuss that one. They're more interested in how you put yourself across and how you work together than the actual topic.
Next was the Toy presentation, I'd read this online and saw the toys in the corner so mentally picked the one I wanted. We had to sell it to the group, basically just reading the box out and the pros of the product. Don't forget to mention whether it needs batteries or not!
Then they had said at one point "if we keep you behind it's because we think you'll be a good cashier and we want to test your skills" but really they just kept behind people they wanted to interview. It wasn't really an interview though they just asked us our availability.
If you pass that they call you in to go in for a second stage interview for an hour, this time you go on the shop floor, a bit on the tills to bag items, a bit to greet customers at the door and a bit going around the shop floor talking to customers.