Error: uninitialized constant MysqlCompat::MysqlRes

After wrestling with this problem for several days I finally got it
nailed. 2 things that I have done that made it work:

   1. sudo env ARCHFLAGS="-arch x86_64" gem install --no-rdoc --no-ri
mysql -- --with-mysql-config=/usr/local/mysql/bin/mysql_config
   2. export DYLD_LIBRARY_PATH="/usr/local/mysql/lib:$DYLD_LIBRARY_PATH"

I'm on Snow Leopard, and have only 1 MySQL (x86_64) 5.5, and 1 ruby
(prepackaged with Snow Leopard) installed.