Plug In Needed for categories

Hey guys, I’m trying to migrate my blog and photolog from MT to WP, and I need a plug in or hack to show the linked title of the previous and next categories, alphabetically, on each category archive page. In MT there were 2 ways to do it:
http://www.scriptygoddess.com/archives/2002/10/29/nextprevious-category-archive/
http://www.bradchoate.com/weblog/2002/10/31/mtcatx
Is there any possibility anyone can come up with a hack or plug in to this? I really need that type of navigation for my photolog and it’s cool to have it on the category pages of the blog.
I hope anyone can help me! Thanks!