The following is a quick howto for when you want to fire up a process as a non-root user on boot under Linux:
Create a script, typically under /usr/bin with something similar to the following:
#!/bin/bash
# invoke your process
/usr/local/process/someprocess
exit
Now, add an entry to /etc/rc.d/rc.local to invoke the command as the non-root user
su – [non-root-user] -c [path-to-shell-script]
Make sure that the exit command is the last thing in the shell script so that you will exit the su and rc.local will continue processing as the root user.