When you have activated the cursor move function by long-pressing the space bar, while still pressing the screen, tap another finger on the screen to move into selection mode.

The prior mention of defining the start and end points of the selection is a bit more tricky and may not even be an actual feature, which involves moving the cursor around in a kind of handoff between start and stop point. That’s trickier to describe because it fellas like it may just be a quirky behavior that can be manipulated.