Can't create PID file on MySQL server, permission denied

The MySQL server won't start and is reporting the following error:

/usr/local/mysql/bin/mysqld: Can't create/write to file '/usr/local/mysql/data/James-Barnhills-Mac-Pro.local.pid' (Errcode: 13)
Can't start server: can't create PID file: Permission denied

All the permissions are set recursively as:

lrwxr-xr-x 1 _mysql wheel 27 Nov 22 09:25 mysql -> mysql-5.5.18-osx10.6-x86_64

but it won't start. I've tried reinstalling several times to no avail.

I'm running as root on Mac OS, and MySQL has read, write, and execute permissions on the "data" folder.