(Apologies for the duplication to anyone who also reads BJF, but someone there was asking about adjusting the KO key count for better accuracy, depending on the shoe depth. He mentioned that Bootlegger has a formula, which I haven't seen, but I have discovered a little "trick" that seems to work pretty well. Since it was on these pages that Brett Harris explained true counting an unbalanced system to me, I thought I'd pass it along here, too.)
I'm not familiar with Bootlegger's formula, but here's an easy way to do what you want with KO, and it works with whatever KO IRCs you are using now, and with any number of decks.
Instead of using the standard KO "key" to raise your bet, use a "current key" that starts out exactly halfway between your IRC and your pivot. If you're using standard KO for a 6-deck game, for example, the IRC is -20 and the pivot is 4, so your current key would start halfway between: -8. But, if you'd rather work with mostly positive numbers, you can always start your IRC at 0, so for a 6-deck shoe your pivot would be 6 * 4 = 24, and your current key would start at 12.
Now, at any point in the shoe, you can look at the discard rack and add 2 to that 12 for every deck you can see -- two decks in the rack, your current key is 16, etc. You don't need to be doing this continually; any time you want to know the current key, just look at the discard rack, think "12" and count up, "14, 16," for every deck
you can see. (If you can estimate two-and-half-decks, add one for the half deck and call it 17, but that's not too important.)
That's all there is to it; that's your current key, and it's equivalent to TKO -2, which is approximately equivalent to HiLo +2, which is worth about +0.5% advantage.
Using that instead of KO's standard keys, you will recognize an advantage earlier in the shoe and also avoid over-betting late in the shoe, which are the two problems with standard KO.
You'll need to adjust your betting ramp "on the fly," but it's not too tough. I just use four levels: a minimum bet when the running count is below the current key; a bet at the current key; a bet to use when the running count is at least halfway between the current key and the pivot; and a max bet at the pivot.