JS to add a link before every download link in blogger blog

Hi I have a blogger blog and I need help creating a "javascript" that will add a certain link before every link in my blogger blog let's say I wanna add linkbucks.cim/ before every rapidshare.com in all posts by script a one that will add to the head or body tags and will work on every post automatically please help and I don't want to use their own script coz I need to add several kinds of links to all posts