I think we can make it jump in a curve by set the player position while jump and fall like this example
http://dl.dropbox.com/u/52040403/bullet%20with%20platform2.capx
If you still need some help, could you please explain in a bit more detail how you'd like him to jump?
Also, if you're using platform behaviour, you can use "Simulate platform pressing right" instead of bullet as well. If you want to. <img src="smileys/smiley1.gif" border="0" align="middle" />