Oh yes it is - in theory. It's amazing what you can do with the EditVoicePak util, whether it's airline callsigns, aircraft names, airfields, whatever.
OK, I wanted Kai Tak. So in the VoicePak util you first ask for the 'sound' Kai. It then searches through all of the sound files and finds every instance of every word which contains that sound. You listen to it, find the best version and then you copy and paste the
segment of the word on file that contains the sound you want.
Then you paste em all together to get the final sound, so getting 'kay' 'gee' 'bee' I would think would not be a problem.
By the way boys, this is ONLY relevant for 2002 - you can't do it with 2004. See what I've been saying?
My ATC now says things like 'cleared to Kai Tak' and '5 miles south of Kai Tak' just it should do

BTW
Once you've found your sound segments, you do it for each voice. It's quite easy once you've cracked the principle