Default [Q] USB mass storage mode gone -- any options?

Has anyone figured out how to enable USB mass storage mode?

I can pull files using "adb pull" however it grabs everything each time.

I have a Mac and I'd like to mount the phone as a volume and use rsync. I did this in the past and it worked great.

Carrier: Sprint / SERO-P
Phone: LG G2
Rom: SlimKat
Radio: Radio (LS980ZVC - M8974A-AAAANAZM-2.0.20046)