I had a look on remote central for HS2 related codes but didn't find much, although I wasn't looking for discrete codes and their is a separate section for tose on the web site.
What you could do is program the pronto to send the discrete code for (say) channel 1 and then send the extra 'down pulses' to cycle the HS2 to the input you require - so that discrete '1', pause, down 1, pause, down 1 should select L2
What you could do is program the pronto to send the discrete code for (say) channel 1 and then send the extra 'down pulses' to cycle the HS2 to the input you require - so that discrete '1', pause, down 1, pause, down 1 should select L2