Hi,
You should be able to build an "ndll". You will need to write some cffi "glue", but from the sounds of it, you could get away with a single function that takes an array of strings (argc,argv).
Then from the haxe code, you use (nme/cpp).Lib.load("yourndll", "yourfunctionname"), and pass in haxe array of strings.
This will use shared libraries - which you need for neko, and also works for cpp. Later, it is easy to convert this to static linking.
If you look at nme as a (big) example of an ndll, the main files are "ExternalInterface.cpp", which you will need your own version of, and the "Build.xml" with uses the hxcpp compiler settings to generate ndlls for platforms supported by hxcpp.
Hugh