Roll 'em up and keep 'em in order just like the old testament tells us, but you don't necessarily have to start the order at Strength. The first number can be placed on the ability of the player's choice (or randomly determined using a 6-sider), but the rest have to follow in the Uniform Ability Order used in your game. Think of the numbers as the fixed prizes around the Wheel fortune and the pointer indicating the starting point. For example, you're rolling up your 6 abilities and you get... [hold on, I'm reaching for my dice]:
11, 14, 8, 10, 13, 9Unaltered AD&D-era ability order (S I W D C Ch--the preferred order here at the ol' Dice-Chucker Cave) dictates that your character would have a high-ish Int and Con, low wisdom, with the rest being middling. But say you really wanted a strongboy fighter type, you could shift the entire number set 1 to the left, giving him a 14 Str. But since this aint no pagan orgy free-for-all, the rest of the number set has to shift as well. The leading 11 now moves to the back of the line at Charisma and the rest take 1 step to the left. Your character now looks like this:
Alternately, to choose starting point at random you could roll a 6 sider to determine where the first number goes, 1 = Str, 2 = Int, etc. (or whatever order you prefer). Using the previous example number set, the player rolls a d6 to determine the starting point... a 3: you would start your number set at the 3rd ability, in this case, wisdom. Using the same dice results in the same order, your character would look like this:
S 13, I 9, W 11, D 14, C 8, Ch 10
Indeed, if you're the kind of DM who pummels parity into your players with a giant hamhock, you could give all the players the same set of numbers and assign each of them--at your whim of course--a different starting point.