Depending on your distribution (you did not mention it), you have a pretty wide area of choice: chkconfig, rcconf, /etc/(rc.d/)rc.local, symlinking startup scripts in init.d\rc.d - but all these require root privilege.
I am assuming you have no access to sudo. These leaves you with just one option, adding a script in crontab that checks if the process is running, and if it not, then start it up. You also gain a kind of availability enhancement (eg. if your process crashes, it is started up again).
My take on this is:
#!/bin/sh
proc=process_name
`ps aux > /tmp/.$proc; awk '/$proc/{print $2}' /tmp/.$proc > /tmp/.x` #if process is alive then copy its PID in .x
if [ -s /tmp/.x ]; then #-s file True if file exists and has a size greater than zero.
echo k #.x is greater than zero => process is alive, all ok
else
/etc/init.d/daemon start _or_whatever_startup file_ #.x was zero, process dead.
fi
`rm -f /tmp/.$proc && rm -f /tmp/.x`