I'd keep in mind that webinars may be a good tool for sharing knowledge but learning how to apply the knowledge in a sales situation takes a lot of time and practice. I don't think you can keep people's attention in a webinar long enough to do much more. If you focused on the business results rather than the training objectives you might try a different approach.

We're dealing with this in the new sales training initiative at ASTD.

The sales department knows best EXACTLY what needs to be built in the program. The training department knows best how to build it.

Facilitation? Try to get someone with sales experience or have a trainer travel with reps for a while before training them.

Best,