rekordbox dj performance as player 1 & 4 in NXS SetUp - BeatSync?

hello,

I'd like to use rekordbox dj (performance mode) on my MacBook (with external 4-Channel-Soundcard) as two extra-Players in my NXS2-Setup. The CDJs and the DJM should stay as standalone-Players. So far this all is not a problem. But ... I'd like to get the BeatSync from the CDJs into the MacBook on rekordbox. How can I do that?

Background for this is, sometimes I need some samples for the mix, which I loop on rekordbox. But I don't use an extra controller for the MacBook, an beatmatching with keyboard and touchpad only isn't comfortable. That's why I wanna use the beat sync on rekordbox.

Thanks for your help.