Select Sessions for Signup During checkout

Issue Summary

My use case is similar to one mentioned here #625366: 1 User signs up for 1 event that has a choice of workshop sessions.

* Users add an event to their cart.
* The enter the normal account info.
* Present them with two sets of sessions to select from.
* They click Next and go on to the Ubercart checkout form

When the store admin looks at their order they will see the event they purchased as well as their sessions they signed up for. The sessions the users signed up for will be listed on their profile pages along with the signup for the conference.

I have tried using product attributes to accomplish this but that has several issues but the main one is that the users are not signed up for the session. It's not easy to display the users that are signed up.

My second attempt is more complex but it should work.

* Create a view of the sessions based on a date/time filter.
* Create a form and populate the radio options with views_get_view_result(session_for_signup, NULL);

ezra-g mentioned using node references but not how to collect this information in the checkout process. Any suggestions or ideas about this use case will be a great help to me.