Dude, you're my hero!
I did have to remove the resistors from my lpt cable to get it to work, though. Using "fc/b", my nand dumps seem to have a lot of differences, but I did manage to make 2 without any errors in the reading process.
My cable is about 3' (which is just long enough to sit the xbox on top of the pc and reach the lpt port), and I did use a switching diode. The box is flashed back to the orig nand, so seems to be fine, but either my dumping isn't consistent for some reason, or fc/b is an inefficient way to compare dumps.
Another box I tried hooking up to read suddenly turns my power brick red when I plug it in; no idea why, as before I started hooking it up, it didn't have a problem....