Answered: What is proper ruby ffi code for this function:
void glutInit(int *argc, char ** argv);
attach_function :glutInit, [:pointer, :pointer], :void
Answered: How to handle array of C-strings? Like a pointer!
Still unanswered:How to change ARGV to match argument type?
If you know how to get "untouched" C argc and argv in Ruby script it would also helped (eg. python have special library for that, I'm not aware of anything similar for Ruby apart from ARGV).