"download a Captivate course on a mobile device"
So then it would be an App, right?
There's no way to do that yet. SCORM requires a live connection to the presenting HTML page, it doesn't allow for offline tracking.
The TinCan spec:
Will allow for this type of offline communication. I assume Adobe/Captivate will support it at some point, but its a new spec and such support is still evolving...and the support has to be between the Captivate lesson AND the LMS (or 'LRS') the lesson is reporting to.
For now, the only option for you to have a web-based CP lesson track to an LMS is to have both components be mobile-compatible for launching with a live net connection. Both exist - mobile-compatible LMS products and CP publishing to HTML (with some limitations), so that would be the approach to tackle for now if such tracking is critical.