ChocksAwayUK.
TG has now strict policy of recruiting own nationals only. Even residency status in Thailand do not allow you to be employed as a flight crew. Eventhough,you'll need to be a qualified pilot already with good flying hours ,speaking good Thai and age below 45.
Then you'll have to go through Psycology Test carried out by SAS team from Scandinavia.
Life will be easier if you have a Thai passport otherwise it is extremely difficult if not impossible.
Having said that Thai now employ a couple of pilot to assist in the new A340 training but this is on a very short term contract only.
So good luck and enjoy in Paradise Thailand.!!