How to burn bootloader/program an ATMega 328P with an external crystal 8 MHz oscilator?
myself as of 3 hours ago.


Get an arduino or similar, install the ArduinoISP sketch 
Connect the two as described here.
Change the board to Arduino Pro or Pro Mini, Processor to 3.3V, 8Mhz, Programmer: Arduino as ISP
Hit burn bootloader button
Load up the sketch that you want on the device
Without changing anything, use "Upload using programmer"
Remove arduino, fix wiring changes required to use as programmer


Committed to Electronics Stackexchange  for posterity.  Or so I can find it when I forget next time...