What about using a corner for them to stand in?. At my house we used to use a chair but they could always see the other kids and none of the kids ever took there time outs seriously. They would even play on the chair, so I took it away and stand them in the corner.

They hate it because they can't see anyone. For time outs at my house no one comes off until they are quiet. I don't believe in the minute per age rule it has never been effective. Then again it depends on the child.

My bitter did time outs in the corner but they never phased her that is why I chose her playpen.

I hope this helps!