You can switch to another workspace from the command line by typing simply:
Workspaces 4
This command will actually take you to workspace #5, since workspaces are numbered starting with 0. While it’s always easiest to use the keyboard shortcuts to switch between workspaces, this can be extremely useful if you want to launch various applications in various workspaces from your UserBootscript. For example:

Workspaces 4
Terminal &
sleep 2
Workspaces 3
NetPositive &
sleep 2
Workspaces 0

The sleep commands may be useful to give an application the opportunity to load fully before moving on.