Provides Drupal Commerce with the ability to sell registrations via the Entity Registrations module.
This module, along with Entity Registrations, is still in beta. That means there can be substantial code changes, although the schema is relatively stable. However, this does not completely remove the possibility of any major changes that will affect interaction between the two modules. Check the issue queue for any possibly existing problems.
Use Drupal Commerce as usual.
If you don't already have a product display set up, create one with a product reference field.
Add a Registration field to the commerce product type you want.
Create a product and set the Registration type (or create one if you haven't already), add a new product display with that reference, and add the settings to the DB as above.