IntelliJ Column Selection using Cursor Keys

Multiline Caret (without mouse)

Windows/Linux: CTRL + CTRL(Hold) + ↑ / ↓

Mac: ⌘ + ⌘(Hold) + ↑ / ↓

ESC will end multiline mode.

Change Multi-caret Hotkey

To add a custom Keymap, CTRL+SHIFT+A, type keymap and click on the one with Settings as subtext. Search for Clone Caret Above and Clone Caret Below.

I mapped mine to ALT+SHIFT+↑ / ↓.

Bonus

Try holding combinations of CTRL, SHIFT, and arrows for improved selection power.

You can do column editing using the Edit | Column Selection Mode.

The shortcut to turn it on/off is Alt+Shift+Insert. You navigate with arrow keys to select blocks of text.