This took a lot of time. In hopes that this will help someone else, I add this link.
Here’s the situation. I have MAMP. For legacy reasons my current MAMP 1.7.2 is in a custom directory. I use ruby. In particular I wanted to use DataMapper in a project with ruby. I wanted to use it with MySQL. That requires do_mysql. It just would not install with all kinds of errors. Well one in particular. It complained of possibly missing headers or libraries. After a long search the above link surfaced from the depths of Google. It almost worked for me. Everything but the last command actually. So for me, the command I ended up using is something like:
sudo env ARCHFLAGS=”-arch i386″ gem install mysql — –with-mysql-dir=/Applications/MAMP_1.7.2/Library –with-mysql-include=/Applications/MAMP_1.7.2/Library/include/mysql –with-mysql-config=/Applications/MAMP_1.7.2/Library/bin/mysql_config
This is OS X 10.5.8 Leopard