Scroll text in a layer or table?

i’m in a situation where i need to have a script that will allow the viewer to scroll through a bunch of text when they rollover an image button.

so i have a space that is about 400x200 pixels to work with, and about 5 paragraphs of information. Is there some JavaScript, CSS, HTML (or otherwise) script that will allow all the overflowing text to be hidden, and then on mouseover (the down arrow image) allow the text to scroll down. also, the reverse will need to happen (scroll up on mouseover the up arrow image).

i’ve seen this done on other sites, just need help getting up to speed on my site. thanks.