Automatic link modification/redirect--changes into affiliate link

For a phpbb2 board, is there anyway to do the following

1. user posts a deeplink (ex. a product on amazon)
2. once posted, your site automatically changes to link to your affiliate link and still goes to that product.

There are many possible affiliates so I think that makes this hard.
I currently have a redirect in place but I do not want to have to manually change every single link. This doesnt even prevent the user from going back in an changing the link back.

in summary, the php will need to
1. analyize the link posted
2. find the appropriate affiliate link to add
3. add affiliate link and replace

here is a site that does this very well. The first link is the topic (topic# 836038, forum #9) and the other 2 are from 2 different posters inside the topic (post 1 and 14). The newegg link changes into an affiliate link when you click on it.

http://forums.slickdeals.net/showthread.php?sduid=0&t=836038
http://slickdeals.net/?sduid=0&sdtid=836038&sdfid=9&u2=http://www.newegg.com/Product/Product.aspx?Item=N82E16814134037
http://slickdeals.net/?sduid=0&sdtid=836038&sdfid=9&u2=http://www.tweaktown.com/articles/1237/9/nvidia_g92_overclocked_gt_vs_gts_512/index.html

PHP:

 

ull have to get urself a custom mod