Transitions in External SWFs

I have just completed the “Transitions in external SWFs” tutorial, and it worked perfectly. However, instead of objects sliding in and out, I used images fading in and out. My question is: is there a simple way to have the fade in, without the fade out? (Eg. when a user clicks on one button, image 1 fades in, and when they click on another button, image 2 fades in over the top of image 1 - without image 1 fading out beforehand.

All help much appreciated.