A Script to assign presets to an of 24 configurable hotkeys.
Go to Tools → Scripts → Hotkey Brushes.
A Window will pop up with a preset chooser and 24 boxes above it. Underneath the boxes is the hotkey the box is associated with.
Select a preset from the chooser and click one of the 24 boxes to set it.
To change the associated hotkey, go to Settings → Configure Krita → Keyboard Shortcuts and then change the Activate Brush Preset actions under Hotkey Brushes
When done, open a file, and press your hotkeys to switch to that preset!