I agree with Angelo and love clicker training. We just train this as a very strict form of Stay. My SAR dogs have several variations of stay, but I have one dog that did film work, and for him, stay meant absolutly no movement. We trained stays the pretty typical way: ask for a position, R+ for longer durations of that position, then thin out (don't R+, ignore) any position w/duration that included any additional movements, then put in the cue (we use both a verbal and visuals.) Clickers work well for marking the coming R+.