"When you say "blank" device, do you mean one that you have only programmed, using the dongle, with your IAP software ?"

Yes, I program the device with the IAP code over the JTAG interface, then use the IAP to download the application code. This has the additional benefit of testing the RS-232 connection at the same time.

There was a lenghty thread on the Cygnal users forum last year about bootloaders which might be of some use if you intend to 'roll your own'.

Regards,
Rob.