TWRP support for the Nexus 9 went live just a bit earlier today, and now the Nexus 6 is getting in on the action. TeamWin Recovery Project version 18.104.22.168 is ready for your flashing pleasure, just head over to the TWRP site to get it. Here, again, is the changelog for TWRP 22.214.171.124, which is the build specifically released to better support Android 5.0 Lollipop.
-Pull in all changes from Android 5.0 lollipop into TWRP -Add decrypt support for Android 5.0 lollipop encrypted partitions including automatic decrypt when the default_password is in use -Revert some changes to exFAT that were breaking exFAT support on some devices -Other minor fixes and updates
To install, you simply need to unlock the bootloader and flash the .img recovery file in fastboot. It's pretty easy stuff.