I tried searching for a quick guide on how to do this and couldn't find anything, although I hear there are details on the documentation site. Anyway, while I think of it, here is a very quick "how to" on setting up a new process type, with a new process class.

1. Create a new SQL table - simple way is to duplicate the create table schema for OpportunityMainMember and make the necessary changes to the column names and constraints. Re-order the columns if required as this is the order they will appear on the screen. Remember to have an OpportunityKey.

2. In BOD create a new BO inherited from the Opportunity object, with the new table linked to the opportunity table and the properties loaded as required. Compile and publish.

3. Go to the OpportunityTypes BO and locate the OpportunityClass property - add the name of the new BO and a description. Compile and Publish.

4. Now go to the Process Type screen from process manager/system setup, and the new class will be available to select.