I'm sure there's a perfectly reasonable explanation as to why someone would want to hack his operation system, but I prefer to stay on the safe side by only telling you that someone (http://www.eznom.net/aximroms/) managed to extract the live ROM from his Dell Axim X50/51 Pocket PC device, to modify it, and to upload it back without completely trashing it.

If you want to take your chance, check out these links:

The long awaited solution on how to use the SD Image Loader for flashing (http://www.aximsite.com/boards/showthread.php?t=112012)
How to create your own flash images for your Axim (http://www.aximsite.com/boards/showthread.php?t=112267)
grab_it - invisible ROM dumper (http://forum.xda-developers.com/viewtopic.php?t=22861&postdays=0&postorder=asc&start=0)