you could use pistons to push it forward on to a block of redstone. or you could put a wooden pressure plate on top of it and then put a dropper a few blocks higher than the pressure plat and then fill the dropper with items then put a daylight sensor on top of the dropper and set it to night or day depending on what you what I mean it all depands on the circumstances.

/entitydata @e[type=tnt] {Fuse:0}

In what context of how? Do you mean when you place a block of tnt it will explode? Or when you punch a tnt block it will explode?