There is no ARM support. There is no ETA for ARM support. You will have to take an existing webcam driver - see here
https://community.leapmotion.com/t/protocole-usb-for-robotics-apps/731
You will have to implement your own feature extraction from the raw images. If you want to try the Leap approach of per-scanline identification of elliptic slices, you can obtain the math for e.g. a least squares approach from the patent filings
https://community.leapmotion.com/t/leap-patent-application-and-other-references/717
Contrast enhancement might be required, see first patent.
To be able to do all this, you will likely have to capture USB traffic from a PC to the Leap, as there is no documentation regarding the Leap-specific host-controller communication (to initialize, select capture mode etc.). Maybe Leap might be willing to assist here?