Transform Scratch - Samples & Preparing the sample

Hi,

Im desperate for some help please. I've seen videos of people using a scratch sample on the xdj-rx, then use the transform effect on it, set it to 1\4 beat, then it can be scratched. 

I was hoping someone can provide a link to a relevant scratch sample and also walk me through preparing the sample on the xdi-rx.

Thanks in advance

Chris