Fixed! The usb-serial adapter linked above showed up today. Steps for those curious or who haven't done this before (like me :)):
- Plugged usb-serial adapter into Macbook Pro
- Installed the driver for the Omega2+ (already had this installed but for those who don't: https://docs.onion.io/omega2-docs/connecting-to-the-omega-terminal.html#connecting-to-the-omega-terminal-serial)
- Set up screen on OSX using Terminal (screen bash, screen /dev/tty.SLAB_USBtoUART 115200)
- Connected the adapter to the Arduino dock serial ports
- Plugged in power to Arduino dock w/ reset held
- Restored via usb drive (downloaded latest firmware from repo, named it omega2.bin, put on root of FAT32 formatted flash drive).