How do I set up Channel Commander?
It's pretty straightforward. To begin with, you need to choose a key which you'll use as your PTT button for Channel Commander and set up whisper-list. Here's how:

In TS3 go to Tools > Whisper Lists (Ctrl+Shift+W)
Click on New (in the bottom-left of the dialog)
Set a Hotkey (the suggestion is: H)
Set Whisper to: to Groups
Set Group Whisper Type: to Channel Commander
Set Group Whisper Target: to Complete Channel Family
Click OK