If you have the previous Dell download couldn't you create an SD Card image using
this tutorial and then flash it to the Axim manually using
this guide?
Edit: sorry, I don't think that would work actually, I just re-read the first link and it's x51 only :(
Unless you can work out how to make (or get a copy of) .nb0 images yourself.
Alternatively, you could install
Linux I suppose. It claims to have USB support, built in (and of course because it is Linux you'd be able to get more information about how things are being detected/or not).