There's also the issue of... if you're using the docking sled serial port, some of those pins are goofy because they aren't part of the serial spec and you'd probably need to make your own cable anyway, as described here.

No, strictly you don't need to make your own cable, but having the parts handy will ensure that you don't get stuck with a ridiculously expensive pre-made cable you can't use. At least if you have the parts, you only need to swap pins instead of driving back to ratshack to exchange the cable.