HEUREKA!
It's up and running.
In addition to Torstens scheme it is necessary to add a wire for power supply.
Therefore, the complete wiring:
Pi+/2/3 --- DAC
J8 P5
2 ---5V----- 1
12 ---BCK---- 3
35 ---LRCK--- 4
40 ---DATA--- 6
39 ---GND---- 7
Of course, nowadays there's no need to patch the kernel. Just enable I2S (HiFiBerry DAC) in Rune's "Settings", reboot and switch to HiFiBerry DAC in "MPD" section.
And now it's time to turn that button
