WPMU-triden 2.1

I'm currently using WPMU-triden 2.1 and need help trying to figure out how to include Buddy Press. I know if I use a BuddyPress theme, I have access to blogs, forums, and community within the site. However, I would prefer to use other themes that are easily customized...yet, I still need that Buddy Press.

So how do I go about creating groups and forums within Buddy Press and then adding them to my site using the theme I am using? How do I get visitors and bloggers on my site to login, create a BuddyPress profile and blog and comment within groups and forums in BP but on my site?