These go into /System/Library/StartupItems:

For MacOSX these two files need to go into:

./BuildCoordinator
./StartupParameters.plist

/System/Library/StartupItems/BuildCoordinator

Your script:
---------------------------------------------------------------------------
#!/bin/sh

. /etc/rc.common

StartService ()
{
        ConsoleMessage "Starting Build Coordinator"
        cd /Users/build/BuildCoordinator
        /usr/bin/perl buildcoordinator.pl 
}

StopService ()
{
        killall -1 buildcoordinator.pl 2> /dev/null
}

RestartService ()
{
        StopService
        StartService
}

RunService "$1"

---------------------------------------------------------------------------
StartupParameters.plist

----
{
  Description   = "Build Coordinator";
  Provides      = ("BuildCoordinator");
  Requires      = ("Network");
  Uses          = ("");
  Preference    = "";
  Messages =
  {
    start = "Starting Build Coordinator";
    stop  = "Stopping Build Coordinator";
    restart  = "Restarting Build Coordinator";
  };
}