Yes, it's possible. You need to create a set of controls (2 each for up & down, 1 pause). Clicking on an image would execute a setTimeout scroll with the appropriate parameters (in the case of normal & fast speed, you would simply move the image by a larger offset). The pause would clear the timeout, thereby pausing the scroll.
For the messages, you need to create a checkDate() function and based upon its results, pull the appropriate message from an array. If you put the array within a js file, the client can change the messages without having to mess with the script itself.
Insofar as 'transparent': I don't know what you mean.
Thank you for the answer. I didn't know what she meant by transparent, either, but as it turns out she means..as opposed to a Java applet with a background. She has a subtle background graphic on the page and wants that to show. Which it does now, but she's been looking at applets and they don't do that. Anyway, I'm no expert on scripts. I can cut and paste and change variables as directed and that's about it. So, I'll be checking your site and others for scripts that do this.