I use the following binding:
CST:Z \S
Unfortunately, this means I can't do things like re'n'ame or use teleport with teleport control, since they require you to press "space" when you select destination tile, and it seems this keybinding overrides them. Pressing space just cancels the command so that rename does not offer the new name prompt, and teleport moves you to a random square (so like pressing 'z' to cancel the selection). This is very annoying since playing with "vi"-style keybinding limits my options, and space key is so big and convenient for frequently used things...