suggestions for long long?

The database library I'm working with has 64 bit integer fields 
(long-long and unsigned-long-long) so I have functions that need this 
as both a parameter and a return value. MCL does not have a long-long 
primitive and it looks like the others don't have one either. Perhaps 
it could be accomplished with an array or struct but I think it will 
need some special care since Mac and Windows use different byte 
ordering.

Thanks for any ideas or suggestions,

John DeSoi, Ph.D.