Hmm.. further investigation.. as per this thread here:
http://bugs.mysql.com/bug.php?id=704
It looks like perhaps the error could have been caused by the MySQL team building the libraries with VC7... However, I would think that would cause problems for anyone else using VC6 now too... wonder if anyone is able to build using VC6 and the exact version of MySQL you are using. You may be able to uninstall/install older version (just 1 release backwards maybe?) and fix it that way...
Another thread of interesting note gave a solution for the problem with the _ftol2 dependency... you can just declare it internally.. but that's really quite klugey.
extern "C" long _ftol( double ); //defined by VC6 C libs
extern "C" long _ftol2( double dblSource ) { return _ftol( dblSource ); }
Just some thoughts. I would go with the MySQL version conflict/fix first and see if that fixes it though.