Use ESXi Image Builder to inject the appropriate VIBs to the image file. Build the ISO and your off to the races.
To hard code an IP address to the installer you can enter the following to the boot config:
ks=http://x.x.x.x/kickstart/myks.cfg ip=x.x.x.x nameserver=x.x.x.x netmask=x.x.x.x gateway=x.x.x.x
Additional details can be found at the ESXi 5.1 Documentation under vSphere Installation Using a Script.