If you don't have FlashBIOS on one of your banks (which allows disc, HDD or HTTP flashing, documented in DJ's link) you can flash with the utility FlashX, giving you full control over the process. Add this to your HDD like any other application and copy the desired BIOS to your HDD for FlashX to read. Available on xbins, should work with all X2 series chips.
The only FTP flashing I am aware of is via the EvoX dashboard. Raw commands can be issued to trigger a flash, although I don't remember all the details on how to do so. I think Martin C or maybe Catalyst had a thread somewhere with the info.
-Whoopin'
