(specifically, I'm using the FRDM-KL82Z on Linux, but it should be generally applicable. When in doubt, carefully watch the videos.)

video on the "Get Software" tab here

1. download the SDK
2. download the Kinetis Design Studio IDE
   • on Ubuntu 64bit, you have to — sudo apt install libc6:i386 libncurses5:i386 libstdc++6:i386
3. download the link titled "J-Link Software and Documentation Pack" here
   • have it configure Kinetis Design Studio (HOW do I do this on Linux?)
4. install the Virtual Serial USB driver (Not required for Linux. Though...
5. install a terminal program
   • (for example, you can install putty on Linux)
   • (how do I know which /dev/ttyS* it shows up as?)

video on the "Build, Run" tab here

• note: if you get the error "Could not determine GDB version after sending: arm-none-eabi-gdb --version", then this is the right solution!
• for the virtual serial port:
  • the speed is 115200
  • if you're using Putty on Windows, then use this method to find out which COM port to use
  • on Linux:
    • TODO: use this "stty" trick!
    • find out the port via — tail -f /var/log/syslog | grep tty — while you plug and unplug the board
    • use Putty from ROOT