I need to review this, too, but multi-acc allocations are primarily tricky with regard to price, and not allocation. Generally, you know how many to buy, but the prices are harder to differentiate with multiple executions.
The simple answer is "don't worry about it, put the contracts in at the average price", which is what you're institution should be able to do for you. Keep in mind that the price is executed based on the number of contracts you submit in the order, so essentially making the value of the trade is the real issue the CFTC has particularly but the SEC's handling of it is different because there are usually a lot more shares and complications with stocks than with futures.
True random allocation should be a rarity, and your broker should help you or you should allocate the contracts with the right price using in house software or a broker that'll do that for you and any clients you might have.
I can also suggest using an excel random number generator and giving the extra contract or contracts to someone in that range. If you have twenty people, break out into 5% increments, and run the random number generator, depending on where it lies that is the account that should get the shares. (Definitely don't just put them in your incentive accounts), but have some record of what you did and this is basically the prescribed procedure. They just want a procedure they can check, and that's all. The above will do that for you and you really shouldn't have that many contracts to randomly allocate so now that I finally articulated to myself how I would handle that, the fact is, I don't ever deal with it, and you probably won't either.