I think thats just a scream to add effect to the song.
"In, out. In, out." starts at around 6:00, becomes really evident at about 6:14 and finishes at 6:53. It's hard to notice sometimes because its sung in time with some really hard guitar.
I actually first noticed it when I was waiting to turn into a car park, with the two lanes marked 'In' and 'Out'. (I'm in Australia so the in is on the left)
Does anyone know what the lyrics are that start around 11:00? Compared to a live version of Third Eye that I have, it sounds like it might be "I open my eyes", but I wanted the input of others.