Well, my calibration skills (or rather, my crappy multimeter) seemed adequate enough to fix the problem I had with sequencer set to KBD mode.
The problem was that it didn't scale properly when I transposed the sequence by pressing the keys. From the lowest F key, I had to go to the next F# (13 semitones) to go an entire octave up. So of course, everything inbetween sounded really awful.
But, with the help of a small screwdriver, a CS-30 service manual and my Voltcraft 91 multimeter I managed to calibrate it well enough.
The calibration procedure includes trimming a couple of trimpots so the voltage at some test points was 0V +/- 50uV. Of course my multimeter has 200mV as minimum range and with only 1 decimal. On top of that I don't know the tolerance so I have no idea how accurate it is.
So, when I saw the value fluctuate around 000.0mV and 000.1mV I figured it's as good as I can get it.
So, now I can transpose those funky 8-step sequences without causing nausea :)
Perhaps I should build a CV/Gate-sequencer? Hmmm...
Anyway, I need a MIDI-CV interface.