Custom index page, only BBCODE issue to solve

[MetalAges]

Hey there everyone! I've spent about 3 hours on this to no avail (I know enough to be dangerous but not enough to get EVERYthing right I guess!).

I have this custom index page: http://ultimatemetal.com/index.php that pulls in stuff from the forum. As you can see in the middle, the only thing that no longer works since upgrading to 3.5 is the BBCode parsing. I know the old include file no longer exists (functions_bbcodeparse.php) and I renamed it to class_bbcode.php. When I only do that I get (I'm using a test page at index-test.php):

Fatal error: Call to undefined function: parse_bbcode() in /home/mahke/public_html/index-test.php on line 30

I know parse_bbcode has seemed to have changed to something along the lines of $bbcode_parser but I can't for the life of me figured how to construct my code to get the BBCode working on this page. Could anyone please provide some guidance? It would be much appreciated!