This is going to get a tad complex, but I bet you can wing it.
 Editor's note: Most of these files are cobbled together from Dnet documentation, so they deserve credit here
Editor's note: Most of these files are cobbled together from Dnet documentation, so they deserve credit here
These will be the nessisary instructions to set up SETI(The CLI of course) to lauch at bootup, basically turning it in to a daemon. You will need admin access to do this.
You must configure SETI first through the normal command line options(start it using ./setiathome) before you set this up.
In /Library/StartupItems, we are going to create a folder called "Seti". Inside that folder, we are going to create 2 text files(you will need BBEdit Lite, or another true text editor for this; TextEdit doesn't save in the right format). One will be "Seti" and the other called "StartupParameters.plist". Below is the content of the files:
[Seti]
#!/bin/sh
. /etc/rc.common
# Don't forget to change buffer/.ini file perms if you wish to run suid'd.
CLIENT_DIR="/Uers/Shared/seti"
CLIENT_FNAME="setiathome"
CLIENT_RUNAS="root" # specifiy the owner of the Seti process
if [ -x "${CLIENT_DIR}/${CLIENT_FNAME}" ]; then
  # first announce what we are going to do.
  ConsoleMessage "Starting Seti client"
  # change directory so we get nicer ps listings.
  wd=`pwd`
  cd "${CLIENT_DIR}"
  # now launch the client 
  sudo -u ${CLIENT_RUNAS} ./${CLIENT_FNAME} >/dev/null &
  cd "$wd"
else
  # announce what happened.
  ConsoleMessage "Seti client disabled"
fi
[END]
[StartupParameters.plist]
{
  Description     = "Seti client";
  Provides        = ("setiathome");
  Requires        = ("Disks", "Resolver");
  Uses            = ("NFS", "Network Time");
  OrderPreference = "None";
  Messages =
  {
    start = "Starting Seti client";
    stop  = "Stopping Seti client";
  };
}
[END]
Now for some notes:
You shouldn't need to modify StartupParameters.plist at all
As for Dnetc...
CLIENT_DIR is the directory the client is in; make sure it's correct 

CLIENT_FNAME is the name of the client itself; also make sure it's correct 

CLIENT_RUNAS is who the client will run as. I reccomend root to bypass all permission issues, as a specific user can get ugly.
The rest of it should be ok, although I'm going to explain one line just to make sense:
sudo -u ${CLIENT_RUNAS} ./${CLIENT_FNAME} > /dev/null &
This command actually starts the client. What will end up being executed is the following as root in the /Users/Shared/seti directory:
./setiathome > /dev/null &
This starts seti, pipes the output in to oblivion, and specifies it as a daemon. 
Once you have these files set up, you can test it by executing the script(./seti) as root. If it's sucessful, the seti client will show up in the ps list(I reccomend ps -ax to see everything). This should be enough to wing it, although I'd be glad to offer any more help if you need it.