hmm, I've never had a boss switching system apart, but usually these things run off a flip-flop switch (it's a type of circuit that basiclly flip-flops...changes state when triggered)
these (usually you'll see them as their own IC) usually have S and R (SET and RESET) inputs -- if you drag one of them high, it will force a switching state (S forces the switch's state hi and R forces it low).
So, when you want a definite "power-up state" , usually one of the S/R input will be tied to ground (so it's always logic lo) and the other will be hooked up to a little RC net off the supply so that, at power-up, you get a logic pulse that SETs or RESETs the flip-flop's state
Boss uses FETs for switching, not an IC flip flop.