<script src="path/to/react-placeholder-shim.js"></script>

/** @jsx React.DOM */
// Assuming the library's dropped in as a script tag.
var Input = placeholderShim.Input;

// try this on IE!
var Demo = React.createClass({
  render: function() {
    return (
      <Input type="text"placeholder="hi"onChange={this.handleChange} />
    )
  },

  handleChange: function(a, b, c) {
    console.log('it all just works!');
  }
});

React.renderComponent(<Demo />, document.body);