Before exporting from Sentinel, Sentinel would first have to be able to detect a character. On the beta server, this would require a 2100.201108240246.1.0 Sentinel manifest file. But manifest files are only generated for releases to live servers.
So Sentinel can't detect characters on the Beta server.
Further, in order to create the data chunk for Mids, Sentinel needs an updated set of rules for exporting to Mids. And the data necessary to generate that file comes from Mids. So, until Mids is *officially* updated, you won't be able to export from Sentinel and import to Mids.
As far as editing the database goes... well, there's a
known issue related to that at the moment.