I struggle with the way parametric roles is currently implemented. Until I can assign groups my opinion is that it will have limited use.
Based on an idea I got from Pareek Arun last year, I wrote this blog on how to get the functionality I think you're looking for. Although it's not using the OOTB parametric role feature, this works and it's flexible in how users and groups can be dynamically assigned based on the rules you specify. Here's the URL: http://www.avioconsulting.com/blog/creating-parametric-roles-using-business-rules
Management chain is a way you can have a series of approval based on the preceding approver's manager. You can input the number of levels (zero based) you want to go up or you can specify the title of the highest level (e.g. "CEO") you want the approvals to go. It assumes you have managers assigned to users in your LDAP.
Hope this gets you going,