I know you asked for a .capx example but, I don't think this really merits it. Below is a screen shot of how I would do it. Simply set the Platform VectorX property and set deceleration to 0 while the character is in the air. When the player is on the ground, you set the deceleration back.
[attachment=0:s6vjutck][/attachment:s6vjutck]
I hope that gets you what you need and good luck with your project.