You can tag recordings while in progress as of release 9.9.0 using the Embedded GUI. Please upgrade your system to release 9.9.0 or better to use this feature.
To tag recordings while in progress you need to be on the Logging screen. Then navigate to the row that displays the data of the recording in progress which you wish to tag. Finally, press the * key to tag the recording.
The * key works as a tag toggle if the screen cursor is on the same row. The first press tags, the second un-tags, the third tags and so on.
For more details see the latest version of the Total Recall VR Embedded GUI User Guide.