SSH tunneling

[oxfordmusic.net]

Just after a bit of advice really to make sure I keep things as secure as 
possible.
I am in the process of setting up an SSH tunnel between 2 RHEL3 boxes for a 
MySQL connection via PHP.
Which users should I use on each box to create the tunnel? Does it matter? 
Do the users need the same privileges as the HTTP user as that is the user 
that will be making the MySQL connection, or can I create the tunnel with a 
low-privileged user?

Thanks

Andy