Install adb enabled setting from zip
For those who are looking for an answer to this question: you can enable adb from a zip file that you install through recovery. I modified Superuser.zip from http://download.chainfire.eu/351/SuperSU/UPDATE-SuperSU-v1.65.zip What I did was I modified system/build.prop and added persist.service.adb.enable=1 at the bottom, I also added ro.setupwizard.mode=DISABLED to disable the setup wizard which gets annoying if you wipe or flash often. Then I added a precompiled sqlite3 (don't have a link, I got it from my company's repo) to system/bin and the line sqlite3 /data/data/com.android.providers.settings/databases/settings.db "UPDATE global SET value=1 WHERE name='adb_enabled'" to system/etc/install-recovery.sh (although some people say modifying settings.db is optional.)
Unfortunately it seems adb still requires you to accept the rsa certificate until you unpack boot.img and modify /default.prop