Use collaborator with GitHub WITHOUT webhooks?

Hi, is it possible to use Collaborator with GitHub but without relying on webhooks?  For networking reasons, we can't.

I see that Collaborator supports "auto-polling" but the docs indicate that's only to discover the existence of new repositories, not to check for updates on existing repositories.  True?

Barring this, would it be possible to configure it as a plain old git SCM instead of GitHub?  In this case, would polling work?  And what functionality would be lost?

Thanks for the guidance here.