Start/stop hot-cue- and sample-button

I'm using the new Pioneer DDJ-RZ with latest rekordbox dj 4.0.
How is it possible to set a start/stop-function to the hot-cue-button or sample-sample?
For example: In the loop-modus of a sample, started with sample-button there is no way to stop it by touching the sample-button for a second time. That's the same by using the hot-cues.