I use dev release and even a little bit old (1715) but as far as I remember I never had problems with any intervalometers when I have switched from/to ALT mode - they just count seconds no matter in which mode... I can't be sure that this is how things were always, but it seems to true now for my camera. I have no enough time now to test stable release...
I can't do many tests now, but a few that I did with my intervalometer: (
http://chdk.setepontos.com/index.php?topic=7757.0 ) show that in general:
- script updates the brightness chart (uses drawings) so it is runing somehow,
- console is not visible,
- script can't take a photo nor press shoot_half.