Sure.
Hold at the apex of contraction until you cannot maintain that position any more , before the eccentric (negative) portion begins. You could do this with standing, seated, or donkey calf raises.
This may take anywhere from 5 seconds to a full minute depending on: Intensity of the preceding set leading up to the isometric contraction, if you achieved concentric failure or not, weight used, etc. The sick part is...it's all mental, no matter how painful it becomes, you must honestly ask yourself, "Has my muscle tissue really failed or has the pain just become too much that I can tolerate this torture no more?" Try to remove yourself physically from the situation. Imagine you are somwhere else, doing something else, not sitting under several plates on the calf raise machine with your calves screaming at you for mercy.
Beware! This is only for the hardcore...no pussies allowed. This is an entirely different ballgame from achieving concentric failure. The only thing more painful and intense would be eccentric failure.