DBI and my.cnf socket file different

[JupiterHost.Net]

Hello Group,

Via the command line I can connect to MySQL and do what I want fine.
Via DBI I get the classic "Can't connect to local MySQL server through 
socket '/tmp/MySQL.sock' (2)"

So MySQL seesmt to not be running but it is! The socket is 
'/usr/local/MySQL/run/MySQL_socket' and is setup that way in my.cnf so 
if I `ln -s /usr/local/MySQL/run/MySQL_socket /tmp/MySQL.sock` then DBI 
can connect().

So the question is, where does DBI get /tmp/MySQL.sock from and can/how 
can/where would I change it to /usr/local/MySQL/run/MySQL_socket or 
would it be better if I change my.cnf to use /tmp/MySQL.soc (if so why)?

Tia :)

Lee.M - JupiterHost.Net