I don't use that scenery (ETO mostly for me), but all you really have to do is go to freeflight, choose the runway you will be using, then hit shift + z to get your co-ordinates. You also need to jot down your heading and base altitude.

Here is a sample, with x's in place of the numbers you need from freeflight. Also, I put x's in place of the runway id which will have to be unique when you add it to your airbases.dat file.


[runway.0]
id=xxxx
heading=xxx
units_across=2
base_lat=xxx* xx.xx'
base_lon=xx* xx.xx'
base_alt=+xxx
takeoff_start_pos=0,0      
takeoff_stop_pos=1600,200
landing_start_pos=5000,350
landing_touchdown_pos=600,0
landing_stop_pos=-250,0