DD,
As I recall, that's Ondanga-Arundel Island in the New Georgea Group of the Central Solomons. It would have been built following the Central Solomon's Campaign to support the Invasion of Bougainville and also the reduction of Rabaul.
This should be the airfield entry for it as well as the lat-long for it's geographic location.
[runway.399]
id=8399
name=SI Ondonga 27L
base_lat=S08 15.86
base_lon=E157 11.68
base_alt=0
heading=270
allegiance=0
units_across=2
takeoff_start_pos=-400,0
takeoff_stop_pos=1600,200
landing_start_pos=5000,350
landing_touchdown_pos=500,0
landing_stop_pos=-250,0
If you use this data in your airfield.dat file, be sure to renumber to a numerical sequence matching your file.