Different Membership Categories...

I'm setting up the Membership plugin on my new site. I understand the concept of Levels of Membership (Level 1, Level 2, Level 3, etc.). That's all fine and good, but I'm confused about something...

I need to have several "levels" of membership that are not part of the hierarchical order. In other words, I have a need for memberships that are separate and distinct from the "standard" membership levels. Specifically, special membership "areas" within the overall forum that a person can join regardless of whether he or she is Level 1, Level 2, Level 3, etc. for the main part of the site. In a sense, I've got a need for a "forum-within-a-forum" and the ability to pay specifically for that.

Is this possible with this plugin? If so, how do I set that up?