It's a two step process:
1. Increase the number of virtual clipboards (at the bottom of the Hotkey editor)
2. Create new hotkey definitions for these virtual clipboards:
- click new
- set action to 'Switch to Virtual Clipboard'
- select the number of the clipboard to change to
- set a hotkey for this new definition
If you still have trouble getting it to work, please contact me directly by email. If anything that might be interesting for the discussion group comes out of it, I'll post it here.