I found these great plastic pushpins that are easily removable.
They fit perfectly in the holes in the doors where the original plastic cups go. I have tested them myself.
So, they will not work with the stock door panels, which have an off-center hole for clipping the metal pushpin.
However, If you are making your own door panels, these could be great. They will secure a panel 1/8" to 1/4" thick.
Just make a 3/8" hole in your door panels, aligned with the hole in the door.
http://www.itw-fastex.com/catalog/index.php/dw/op/a/6/c/16/p/4?m=no
Item # 30080016
You can get a free sample of 15 of them, which should be enough to do 2 doors.
Hope this helps someone.