Hi I have alpha track running on Sierra and here is what to do (found all info on web): Alphatrack on Sierra
UPDATE: woohoo - got it working with Logic 10.3.1 and OSX 10.11.x thanks to a generous user on another forum. Copied & edited the pertinent bits here:
Disable SIP by restarting your Mac, holding down Command + R to boot from the Restore volume. When booted, go the the Utilities menu up at the top and choose Terminal. Type in the following:
csrutil disable; reboot
Your Mac will reboot itself and SIP will be off.
Download the following archive: http://motunation.com/files/AlphaTrack_OSX10.11.1_Installation.zip
This archive when expanded should be self explanatory. It has all the necessary files for AlphaTrack and shows where to copy them. It also contains what you'll need including an app called Kext Utility. (See: http://mac.softpedia.com/get/System-Utilities/Kext-Utility.shtml
You can't just copy the actual .kext file. Use the Kext Utility app to install the kext file so that the system will load it properly. Launch Kext Utility and drag the file, FrontierDesignAlphaTrack.kext onto its window and it will install. Wait till it is finished and then quit the app. On reboot, the AlphaTrack should work.
Keep in mind, this is dependent on also having the 64-bit compatible control surface bundle for Logic:
https://www.frontierdesign.com/download/plugin/AlphaTrack/AlphaTrack_Logic_1.3.zipm - see their documentation about where to put that bundle.
This worked for me. However, given the litigious nature of society these days, I must warn you to backup first and I can take no responsibility if it doesn't work right for you, etc. - do this at your own risk.