The Kindle 1 is very fast at this. Because it uses the LCD cursor which is the little silver bar thing that runs along the right side of the screen.
You scroll the bar up to the first line you want to highlight, press the button, choose highlight from the menu, then choose the last line, and press select. Done.
As for the K2... well, you'll have to wait till someone gets one to answer the question about that. But, I assume it would be similar, except you are using the joystick to select the first place/word.