Linux – temporarily disable touchpad and keyboad, i.e. babyproofing the linux laptop

Following up with this other question, how can I temporarily disable the touchpad (both movements and buttons) as well as the keyboard in Linux Ubuntu Hardy? I mean, there is a menu for disabling the mouse (and there might be one for the keyboard), but I don't want to lock myself out. The best would be an option to decide which keys on the keyboard I want to be working (e.g. arrows to scroll the page I'm reading) and with a fast keys combination to lock/unlock (e.g. one not easily pushed by my toddler little hands: left-shift + ESC + right-shift + backspace + space)

Edit: I get the tumbleweed badge with this question, but it was seen and even starred? Does anybody have an answer? Let's try with a bounty….