Scrolling text question

Hello all,
This is my first post, recently found these forums.

Anyway, how would I go about making text alpha blended at the top and bottom of the field such as … I’ve seen a couple of sites that have done this and am wondering if it’s just a rectangle with an alpha of 50% or so overlapping the top and bottom of the field. Either way it’s a cool effect. If anyone can help me out that would be great. Thanks.