I've flown in there a number of times. No training I know of.
There is a considerable amount of paperwork to be done on each movement, which takes 1-2 hours in two separate offices (Greek style job creation makes the toothpaste-confiscating security guards at Norwich look like M Thatcher) and costs of about Euro 90.
A lovely place to fly to and stay, and an essential port of entry into Greece (has avgas) but I have not found any way to e.g. be based there and fly from there repeatedly, without going through the above process each time.
I have sent you a PM.