After spending a frustrating day messing with a Lexar Media USB enabled 4X compact flash to get the WebPal to pivot_root to it, I gave up. I tried the same thing with a SanDisk device and it worked fine! My advice is to stay away from Lexar compact flash!
I have also noticed a "feature" with the SanDisk CF devices, you can hotswap them and they will come up in IDE mode (reads pin 9). Lexar won't do this, you have to power-cycle the Lexar to get it to properly read pin 9 (IDE mode select).