ok, the optiboot bootloader page says
Compatible with 168 and 328 Arduinos including Lilypad, Pro, Nano
and the A6 and A7 are defined in pins_arduino.h so I suppose they should work as it appears to be independent of the bootloader.
I could not find anyone posting that this was successfully done. and I can't tell for sure if Bill Westfield's optiloader program will burn the optiboot bootloader onto a nano.