Actually I wrote a windows VB5 based alternative to the original atmel software, I sent it in but sadly it either got lost or forgotten about. Worked nicely for me but it has its limitations.

By the way, the atmel design has a connection missing, chip U4 pin 9 must connect to pin26 on the 40 pin connector. Without this connection programming chips with more than 8k is not possible and programming the 8252 is totally impossible as you end up programming the eeprom continuously never touching the flash at all. Atmel included the signal in their software but never updated the schematic.