Sorry missed this, but yes - totally doable, but will cost a bit!!
One way with Harvestman / Industrial Music Electronics Stillson Hammer and Argos Bleak.
Set the chords up on Argos Bleak
Set 4 steps, one each to the correct voltage to trigger the chord in Argos Bleak, then set to play on random on Stillson hammer MK][ for 25% probability. To increase the probability distribute the voltages across the number of steps in your sequence - think about what having two steps on the same voltage in a 5 step sequence on random would do to the probability.
-- Kel_
I've had a look at this - at last! :-) - and as best my befuddled brain can gather, this gives each chord a certain probability of sounding. In other words, each chord has its own probability which is in no way influenced by any other chord, particularly the chord that's currently playing.
Is that right?
If not, ignore the rest of this post :-)
What I'd like to try is for the current chord to affect the probability of the next one. Eg, if the current chord is C, then Am might have a 20% chance of playing and G a 60% chance. If the current chord was Dm, Am might have a 50% chance of playing, etc.