Longer tween durations (5+)

I want to make a small ad banner (only 120px) with many photos.
These photos should slide through the banner from right to left.
I use the "slide" pattern but for my idea the tween duration is too short.

Any idea, how to move up easy this limited value to make the effect just slower?

Thanks
Sebastian

Here's an idea:
Before you run this code you need to have a FlashEff component on the stage and it must have the instanceName namde "fe". Put it over a movieclip and then go to the panel and select the FESSlide effect for the show effect, then just add the code below and compile. There are a bunch of other ways to do this so let me know if this does not work out for you.
var pattern = fe.showTransition
fe._targetInstanceName = 'InstanceName_0';
fe.showAutoPlay = false;
fe.hideAutoPlay = false;
fe.showTransition = pattern
fe.hideTransition = pattern
//pattern.preset = 5;
pattern.tweenDuration = 15;
pattern.positionX = 150;
pattern.positionY = 150;
fe.show();