At Chiang Mai the process is simple. Unfortunately the wait times are horrendous, arrived 6am, finished at 2pm.
I hand over the school paperwork with 1900 baht paperclipped and passport (and 2 x photos), I greet IO in Thai and Wei, then stand for 15 minutes of processing.
Photo taken and told to sit down for anything upto an hour whilst your passport gets a second signature by a higher ranked IO.