Ok, this is how i do it, other people may have different methods so please feel free to contribute (or tell me i'm full of crap).
I just had another go at remaking the sound using just logic plugs so i can give you an example. I'll try and make it simple so you get the idea and can build on it from there.
I think the key to a massive angry fat dirty bass sound is in multi band processing (and side chaining, but that comes in later). If you don't have a multiband distortion like Izotope Trash, go get it now! Otherwise you can do it old skool (more fun) by setting up busses and filtering them. Start with the ES2 preset called Monster Sine. Disable the master output on the channel strip and send it instead to 2 busses (you can use more, but 2 will be fine for this example).
On the first bus insert an EQ and set a low pass at about 80Hz, 48dB/8ve. On the second, insert a high pass at 80Hz, 48 dB/8ve. Basically you're separating the sound into the 1: sub frequencies and 2: everything else (you can add as many bands as you want, just make a new send and filter it as you please. Also have a play around with these cutoffs, 80 is a good place to start but adjust it according to the sound you want).
Next take your overdrive (i'd reccomend clipdist) and insert it on the higher band, leaving the lower band clean. Add as much drive as you want, go crazy if you want a super dirty sound. Because you're not driving the low end it'll still sound huge, but you get the full drive from the lower mid to treble instead. Now balance the two (or more) bands in level using the aux channel faders.
Next sidechain compress the heck out it, i think the VCA model on Logic compressor is great for bass side chaining.
You should be able to get an approximation of that My People sound pretty easily this way, it won't quite be the same, i say get NI Massive and Trash if you want better though. I've got something that sounds ALMOST exactly the same.
Hope that makes sense, let me know if it doesn't though.