permissions problem on startup

[John Jolet]

I'm having a problem that I saw in the archives someone else having,  
but I couldn't find a solution.  Running on gentoo with postfix.  If  
I set the Run As user to postfix, I get: Cannot open config file /opt/ 
MailScanner/etc/MailScanner.conf, Permission denied at /opt/ 
MailScanner/lib/MailScanner/Config.pm line 597.

now, that poster said he made it work by giving postfix user a shell,  
but that doesn't seem to work for me.  if I start it as root, it  
works, but then postfix would need to run as root.  postfix:postfix  
owns MailScanner.conf, and it can be read by postfix....  the  
mailscanner program opens it like 10 times, then switches uid and gid  
to postfix, and then can't open it.  or says it can't.  what's going  
on here?