Multi line text rollovers

If I have a bunch of text, like a list. and each line of text I want to have a rollover effect. maybe a bar fades in and out acting as a background to the text of a single line. or maybe the bar grows in length. I tried doing this, and it seems that I need to make a seperate movie clip for each line of text. is there a way I can just type out all my text within one text box, and still have an effect for each indevidual line of text? thanks. I hope I 'm describing it well enough.