First, make sure the LiveLink is broadcasting properly. We cover this in another article.
Then, go to Window → Cinematics → Take Recorder
That will open up Take Recorder window, click on Source → From Actor, and then select the character in your scene being driven by the Live Link data.
Make sure the data is streaming, and then when you are ready, click the red circle to Record. Click Stop when you are done
Take is stored by default in the Take Browser. To access the Take Browser, go to Window → Cinematics → Take Browser. Every take creates 3 different files: a Level Sequence, an Animation Track, and an Animation Sequence.
The Level Sequence functions just like any other sequence and if you click on it in the sequencer you can access the Animation Track.
The Animation Track is where you can edit the keyframes if desired. You can also drag the Animation Track into other Sequences.
The Animation Sequence created functions like any other Animation Sequence. In the Animation Sequence Settings, make sure Force Root Lock is turned off.