I directly took the head of development of optiboot itself. See: Google Code Archive - Long-term storage for Google Code Project Hosting.
The arduino project only pulls changes from there if they are relevant to mcu's supported by arduino, so for the atmega164 and friends, we're better off at optiboot.
It goes like this:
hg clone https://code.google.com/p/optiboot/
cd optiboot
patch -p1 < patch_file
cd optiboot/bootloaders/optiboot
./makeall